A large national cohort of French patients with chronic recurrent multifocal osteitis

Challenges in the imaging and diagnosis of chronic non-bacterial osteomyelitis (CNO)

Chronic non-bacterial osteomyelitis (CNO) is a benign skeletal disorder of childhood and adolescence characterised by sterile bone inflammation that results in chronic insidious bone pain. Although it is increasingly recognised, many challenges remain in its diagnosis with patients waiting 15-24 months for diagnosis from the time of symptom onset. Prompt identification and treatment are key to reducing morbidity from CNO, which affects school attendance and can result in chronic limb or spine deformities. Identifying its imaging features, particularly its characteristic lesion distribution on whole-body MRI, remains key to diagnosis. Image-guided biopsy is also required in many cases, particularly those with clinical uncertainty around the diagnosis. We present a review of the challenges encountered in the diagnosis of CNO from a critical appraisal of the literature and our experience as a national paediatric sarcoma, rheumatology and orthopaedic centre. This review hopes to inform radiology colleagues involved in the evaluation of potential CNO patients by discussing its imaging appearances, typical MRI phenotypes, potential mimics and the role of image-guided biopsy.

Chronic non-bacterial osteomyelitis in children- five-year standardized follow-up of a prospective observational cohort in the pre-biological era

BACKGROUND

This prospective, long-term observational study, initiated in 2002, aimed to characterize clinical and laboratory data, whole body MRI detected lesions, and treatment responses in 37 juvenile patients with chronic non-bacterial osteomyelitis at a time when biological DMARDs were not yet standard therapy.

METHODS

Patients were assessed at baseline and at 1 (without MRI), 3, 6, 12, 18, 24, 36, 48, 60 months. All patients received naproxen as first-line therapy. Clinical management allowed for escalation to sulfasalazine, pamidronate, and glucocorticoids as needed. Treatment response was evaluated using the pedCNO disease activity score (30/50/70/90% improvement). Further composite numeric disease activity (DA) scores- the CARRA CDAS and a new MRI DAS - were applied.

RESULTS

The mean age at disease onset was 10.8 years, with a diagnostic delay of 5.8 months. Naproxen was the initial treatment in all patients. Second-line therapy was initiated in 10 patients due to inadequate improvement in physician global assessment of disease activity, patient-reported overall wellbeing or MRI lesions. Escalated therapies included sulfasalazine (n = 10), bisphosphonates (n = 1), methotrexate (n = 1), and short- (< 4 wks) or long-term oral glucocorticoids (n = 5 and n = 3, respectively). The mean number of clinical lesions decreased from 2.1 to 0.4 at 12 months and reached 0.15 at 60 months. MRI-detected lesions declined from 5.0 to 2.25 at 12 months and to 1.1 at 60 months.

CONCLUSION

Most children experienced favourable long-term outcomes. Clinical improvement occurred more rapidly than radiologic resolution. Patients with insufficient response to NSAIDs should be considered for a treat-to-target approach, including the use of conventional and biologic DMARDs.

TRIAL REGISTRATION

A trial registration EUDRA CT was not available at the time the study was started. Informed consent was given by all parents.

EULAR/American College of Rheumatology Classification Criteria for Pediatric Chronic Nonbacterial Osteomyelitis

OBJECTIVE

To develop and validate classification criteria for pediatric chronic nonbacterial osteomyelitis (CNO) jointly supported by EULAR and the American College of Rheumatology (ACR).

METHODS

This international initiative had 4 phases: (1) candidate items were proposed in a survey of pediatric rheumatologists, (2) criteria definition and reduction by Delphi and nominal group technique exercises, (3) criteria weighting using multicriteria decision analysis, and (4) refinement of weights and threshold score in a development cohort of 441 patients and validation in another cohort of 514 patients.

RESULTS

The new EULAR/ACR classification criteria for CNO require typical radiographic or magnetic resonance imaging findings and bone pain as an obligatory entry criterion and exclusion criteria of malignancy, infection, vitamin C deficiency, and hypophosphatasia, followed by additive weighted criteria in 5 clinical (site of bone lesions, pattern of bone lesions, age at onset, coexisting conditions, fever) and 4 pathology/laboratory domains (bone biopsy findings if done, anemia, C-reactive protein level, and erythrocyte sedimentation rate). A total score ≥55 is required for classification as CNO. The new criteria had a sensitivity of 82% and specificity of 98% in the validation cohort.

CONCLUSION

These new classification criteria for pediatric CNO developed with international input reflect current views about CNO, have high specificity and good sensitivity, and provide a key foundation for future CNO research.

Comparative study of radio-clinical parameters in pediatric forms of fibrous dysplasia and chronic recurrent multifocal osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory disease with clinical and radiological symptoms that overlap with fibrous dysplasia (FD), particularly in children. This study aimed to compare the clinical and radiological features of craniofacial CRMO and FD in a pediatric population. Seven children with CRMO and 14 with FD were retrospectively identified in our tertiary centre between 2012 and 2022. Their clinical, radiological, and biological (when available) data were collected. Two experienced radiologists reviewed imaging modalities following a standardized form, including characteristics of the lesions, soft-tissue involvement, and signal abnormalities (MRI). Swelling and pain were common symptoms in the CRMO group (7/7 and 5/5, respectively), compared with 11/14 and 2/14 patients in the FD group. Imaging (CT scan) comparisons revealed a predominance of erosive lesions, cortical interruption, periosteal apposition, and soft-tissue involvement in CRMO compared with FD (4/5 vs 0/6, p1 = 0.01; 5/5 vs 1/6, p2 = 0.01; 5/5 vs 0/6, p3 = 0.002; and 4/5 vs 0/6, p4 = 0.02, respectively). Hyperosteosis was mainly associated with FD lesions (6/6 vs 2/5, p = 0.06). Knowledge of the clinical and radiographic differences between CRMO and FD could help clinicians to differentiate between the two diseases.

[Arthritis and osteomyelitis in childhood and adolescence-Bacterial and nonbacterial]

Bacterial arthritis and osteomyelitis are usually acute diseases, which in this way differ from the often insidious course of nonbacterial osteomyelitis; however, there is often an overlap both in less acute courses of bacterial illnesses and also in nonbacterial osteitis. The overlapping clinical phenomena can be explained by similar pathophysiological processes. In bacteria-related illnesses the identification of the pathogen and empirical or targeted anti-infectious treatment are prioritized, whereas no triggering agent is known for nonbacterial diseases. The diagnostics are based on the exclusion of differential diagnoses, clinical scores and magnetic resonance imaging (MRI). An activity-adapted anti-inflammatory treatment is indicated.

Evolution of bone lesions in adults with chronic nonbacterial osteitis (CNO): A long-term follow-up study

OBJECTIVES

Chronic nonbacterial osteitis (CNO) is a rare disease characterised by sterile bone inflammation. Little is known about the evolution of bone lesions, especially for the adult variant of the disease (adult CNO). We therefore aimed to characterize the radiologic course of adult CNO.

METHODS

We conducted a cohort study among confirmed adults with CNO, treated at the Dutch national CNO referral centre between 1992 and 2023. Imaging reports from the first-performed radiological scan (baseline) to the last available scan (end of follow-up) were systematically reviewed for lesion location and radiologic features (sclerosis, hyperostosis, erosions, ankylosis). Incidence rates (IRs) for new lesions, progression, and regression of existing lesions were estimated using the Poisson method. Kaplan-Meier curves were used to visualize cumulative incidence, and Poisson regression models assessed associations between patient characteristics and the outcomes.

RESULTS

The study included 182 adult CNO patients with a mean follow-up of 6.1 ± 5.2 years, treated with nonsteroidal anti-inflammatory drugs or cyclooxygenase-inhibitors and/or intravenous bisphosphonates or tumour necrosis factor alpha inhibitors. The most common pattern was sole involvement of the anterior chest wall (84 %). IRs per 100 person-years were 4 (95 % CI 3-5) (new lesions), 7 (6-9) (progression), and 1 (0.3.-1) (regression). Among patients with anterior chest wall involvement only (n = 147), one person developed a lesion outside this area (IR 0.3 (0.06-1)). At 2 years, cumulative incidence of new lesion development and progression were 2 % (0-5) and 7 % (3-10), increasing to 11 % (5-17) and 29 % (20-36) at 5 years, and 36 % (23-48) and 56 % (43-64) at 10 years. No associations were found between clinical characteristics at baseline and these outcomes.

CONCLUSIONS

The development of new bone lesions in treated adult CNO patients is typically confined to previously affected regions, primarily the anterior chest wall. Progression of structural changes occurs in the majority of patients after longer follow-up. These findings can be used for prognostic counselling, and suggest that routine whole-body imaging may not be necessary for most patients during follow-up.

Incidence of chronic recurrent multifocal osteomyelitis in children and adolescents in the UK and Republic of Ireland

OBJECTIVES

Chronic recurrent multifocal osteomyelitis (CRMO), also known as chronic non-bacterial osteomyelitis (CNO), is a rare autoinflammatory condition affecting the bones in children and teenagers. The actual incidence of CRMO remains uncertain. The objective of this study was to identify the incidence of CRMO in children and young people under the age of 16 years in the United Kingdom (UK) and Republic of Ireland (ROI). We also aimed to delineate the demographics, clinical presentation, investigations, initial management and healthcare needs for children and adolescents with CRMO.

METHODS

We conducted monthly surveys among all paediatric consultants and paediatric orthopaedic surgeons to identify patients newly diagnosed with CRMO between October 2020 and November 2022. A standardized questionnaire was sent to reporting clinicians to collect further information.

RESULTS

Over the surveillance period, 288 patients were reported, among which, 165 confirmed and 20 probable cases were included in the analysis. The highest incidences were among 8-10 year-olds. A two-to-one female-to-male difference in incidence was observed, and male patients were more likely to present with multifocal disease. A negative correlation was observed between reporting clavicular and leg pain. Investigation-wise, 80.0% of patients were reported to have undergone whole-body MRI and 51.1% had bone biopsies. The most common initial treatments were NSAIDs (93.9%) and bisphosphonates (44.8%).

CONCLUSION

This study estimates an average annual CRMO incidence of 0.65 cases per 100 000 children and adolescents in the UK and ROI. These findings establish a crucial baseline for ongoing research and improvement in the care of individuals with CRMO.

TNF-alpha blockade in primary chronic non-bacterial osteomyelitis of the mandible

OBJECTIVES

Primary chronic non-bacterial osteomyelitis of the mandible (CNOM) is a rare auto-inflammatory disease of unknown aetiology that bears pathophysiological resemblance to both SAPHO syndrome in adults and chronic recurrent multifocal osteomyelitis (CRMO) in children. Both SAPHO and CRMO respond to TNF-α blockade. Previously reported treatment regimens in CNOM including NSAIDs, corticosteroids, antibiotics, anti-resorptive therapy and surgery all bear disappointing results. TNF-α blockade is suggested as a treatment option by some experts but this is not backed by any clinical data. We sought to retrospectively and exhaustively report our experience of anti-TNF-α therapy in refractory CNOM.

METHODS

Fifteen patients with refractory CNOM and high disease burden were referred to our centre. TNF-α blockade was attempted in 10 cases, given its efficacy in neighbouring diseases, its good tolerance profile and failure of previous treatment strategies. We herein retrospectively report detailed outcomes for all patients having received anti-TNF-α therapy for this indication in our centre.

RESULTS

TNF-α-targeting therapy resulted in a rapid and sustained remission in a majority of patients with CNOM, without serious adverse events. Treatment was tapered and stopped without relapse in some patients despite a refractory course of several years. Male sex seems to be associated with a poorer outcome.

CONCLUSION

Our results suggest that blocking TNF-α is efficient and safe in CNOM.

Chronic Non-Bacterial Osteomyelitis (CNO) in a Tertiary Center in Southern Italy: Response to Treatment and Outcome Stratification

Background/Objectives: Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory disease characterized by chronic sterile uni- or multifocal osteomyelitis. The treatment of CNO is mostly empirical and the outcome of the disease has not yet been standardized. The aims of this study were to correlate clinically active lesions with radiological signs of inflammation and to evaluate the outcomes in terms of symptoms and radiological signs with Whole Body Magnetic Resonance Imaging (WB-MRI) based on the treatment line used. Methods: A retrospective, observational cohort study of 20 CNO patients, recruited from a single tertiary center in southern Italy, was conducted. Patients included in the study were treated based on the "step-up" approach and were guided by the "treat-to-target" strategy as well as by the response to therapy. The outcome measure was stratified into four different groups, defined by a "Delphy consensus", depending on the symptoms and the presence of bone lesions in WB-MRI, compared with the therapy carried out. Results: Pain was the most common presenting symptom of the disease. Only 15% of our patients reported long-term complications. WB-MRI was performed for each patient both at diagnosis and during follow-up. At onset, the site most affected by the disease was the tibia. All patients who reached a 5-year follow-up (30%, n = 6) achieved a complete disease remission. Conclusions: The standardized "step-up" treatment approach in our cohort proved effective in disease management with disease control or remission in nearly 90% of patients at one year from diagnosis.

Associated diseases and their effects on disease course in patients with chronic non-bacterial osteomyelitis: retrospective experience from a single center

OBJECTIVE

Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory bone disease associated with other chronic inflammatory diseases such as familial Mediterranean fever (FMF), juvenile idiopathic arthritis (JIA), spondylarthropathies, inflammatory bowel disease (IBD), and pyoderma gangrenosum. We aimed to describe the clinical and follow-up characteristics of patients with CNO and to compare findings between patients with and without comorbidities.

METHODS

The clinical records of patients with CNO who were followed up in our pediatric rheumatology clinic between 2018 and 2023 were reviewed. Patients were divided into two groups according to the presence or absence of comorbidities. The clinical, laboratory, and radiological characteristics and treatments of the groups were compared.

RESULTS

The study included 40 patients (65% male) diagnosed with CNO. The median (IQR) age at symptom onset was 10 (6.4) and at diagnosis was 11.5 (5.9) years. Fourteen (35%) patients had comorbidities. The comorbidities were FMF (n = 9), IBD (n = 3), uveitis (n = 3), psoriasis (n = 1) and acne conglabatae (n = 2). The group with comorbidities had higher number of bones involved (3 or more bones) (78.6% versus 42.3%) (p = 0.028), and 78.6% of patients with comorbidities received biologic treatment, while only 23.1% of patients without comorbidities were treated with biologics (p = 0.001).

CONCLUSION

Familial Mediterranean fever, uveitis, IBD, psoriasis and acne conglabata were found to be the clinical conditions associated with CNO. Patients with CNO who had comorbidities appeared to have a more severe phenotype of the disease accompanied with more bone involvement and requiring more biologic treatment. Key Points • Chronic non-bacterial osteomyelitis (CNO), an auto-inflammatory bone disease, can be seen in association with other inflammatory conditions such as familial Mediterranean fever (FMF), uveitis, inflammatory bowel disease (IBD), psoriasis, and acne conglobata. • If CNO is associated with another inflammatory disease, the number of bones involved may be higher and patients may need more intensive treatments, such as biologics. • CNO may coexist with one or more inflammatory diseases, which may exacerbate the disease phenotype.

TEMPORARY REMOVAL: EULAR/ACR classification criteria for paediatric chronic nonbacterial osteomyelitis (CNO)

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A child with Chronic Nonbacterial Osteomyelitis and celiac disease: accidental association or two different aspects of the same condition?

BACKGROUND

Chronic Nonbacterial Osteomyelitis (CNO) is a rare auto-inflammatory disease that mainly affects children, and manifests with single or multiple painful bone lesions. Due to the lack of specific laboratory markers, CNO diagnosis is a matter of exclusion from different conditions, first and foremost bacterial osteomyelitis and malignancies. Whole Body Magnetic Resonance (WBMR) and bone biopsy are the gold standard for the diagnosis. Although the association with Inflammatory Bowel Disease (IBD) has been reported in the literature, cases of CNO in celiac patients have never been described before.

CASE PRESENTATION

We report about a girl of 3 years and 8 months of age who presented with severe bone pain, slight increase of inflammatory markers, micro-hematuria and high calprotectin values. Her personal medical history was uneventful, apart from low weight growth. She had never complained of abdominal pain or other gastro-intestinal symptoms. WBMR showed the classical features of multifocal CNO, and biopsy confirmed the diagnosis. Celiac disease (CD) was suspected on the basis of antibody screening, and confirmed by gut biopsy. With gluten-free diet the patient achieved rapid and complete symptom remission together with healing of all the bone lesions proven by WBMR. Three years after the onset of the disease the girl is healthy and totally asymptomatic, still on clinical and radiological follow-up.

CONCLUSIONS

Based on our experience, the diagnostic work-up of new cases of CNO should include the screening test for CD and, according to the literature, the possibility of IBD should also be properly ruled out. When CNO and CD coexist, gluten-free diet, combined with antinflammatory therapy, could be able to completely reverse bone lesions, shortening the duration of medical treatment. Because the diseases' onset is seldom simultaneous, patients with CNO and IBD deserve a properly extended follow-up. Finally, the analysis of the relationship between CNO and autoimmune intestinal diseases provides a unique opportunity to understand the pathophysiological pro-inflammatory network underlying both types of disorders and it is necessary to make the most suitable therapeutic choice.

Factors associated with treatment response in chronic nonbacterial osteomyelitis at a single center: a retrospective cohort study

BACKGROUND

NSAIDs are commonly used as first line therapy in chronic nonbacterial osteomyelitis (CNO) but are not effective for all patients. The objective of this study was to identify clinical variables associated with NSAID monotherapy response versus requiring second-line medication in a single-center cohort of patients with CNO.

METHODS

The charts of children with CNO who attended a CNO clinic at a quaternary care center between 1/1/05 and 7/31/21 were retrospectively reviewed. Patients were divided into 3 groups: NSAID-short (NSAID monotherapy for 3 to < 7 months), NSAID-long (NSAID monotherapy for ≥ 7 months), or second-line treatment. Patients were also categorized by which bodily regions were affected by CNO. Multiple linear and logistic regression models were constructed to predict total NSAID monotherapy days and the odds of needing second-line treatment, respectively. These models were optimized using variable combinations that minimized multicollinearity and maximized predictive power, as indicated by minimized AIC values.

RESULTS

One-hundred-sixty-four patients fulfilled inclusion criteria. Thirty-two patients were in the NSAID-short group, 62 in the NSAID-long group, and 70 in the second-line treatment group. Comparing the two NSAID groups showed that patients with unifocal disease at diagnosis required 47% fewer days of NSAIDs than those with multifocal disease. Results from logistic regression indicated that for each additional region affected, the odds of needing second line treatment increased by 1.94 times (p = 0.01) and that patients with symmetric bone lesions were 6.86 times more likely to require second-line treatment (p < 0.001).

CONCLUSIONS

Patients with unifocal CNO involvement at diagnosis were more likely to require shorter NSAID treatment. Patients with more regions affected and those with symmetric bone lesions were more likely to require second-line treatment.

Chronic Noninfectious Osteomyelitis: A Review of Imaging Findings

Chronic noninfectious osteomyelitis or chronic nonbacterial osteomyelitis (CNO), also known as chronic recurrent multifocal osteomyelitis, is an autoinflammatory bone disorder primarily affecting the pediatric age group. Currently, it is diagnosed on the basis of clinical, laboratory, and imaging features. Imaging plays a crucial role in the diagnosis and follow-up of CNO with whole body magnetic resonance imaging (WBMRI) being the main modality. Radiographs assist in exclusion of common differential diagnoses like infections and malignancy. WBMRI aids in disease detection and exclusion of differential diagnoses, identifies additional lesions, and has a role in ascertaining the pattern of bony involvement which helps with prognostication and grading. Recent recognition of specific morphological and distribution patterns on WBMRI is increasingly allowing an upfront diagnosis of this entity to be made on imaging alone. It is also helpful for assessment of response to therapy during follow-up. This review aims to summarize the role of imaging in the evaluation of CNO, with special emphasis on WBMRI in its assessment.

Chronic Recurrent Multifocal Osteomyelitis (CRMO): The Deceptive Disease That Mimics Sarcoma Radiologically but Promises a Complete Recovery

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare and distinct form of chronic non-bacterial osteomyelitis with an unknown etiology. This 11-year-old Asian girl presented with a painful swelling in her right arm, which was suspected to be a Ewing's sarcoma based on radiological findings. The lesion appeared as a unifocal destructive bone lesion in the proximal diaphyseal region of the right humerus, accompanied by periosteal reaction and soft tissue involvement. She was otherwise clinically well, except for the elevated C-reactive protein, erythrocyte sedimentation rate and alkaline phosphatase. Due to the clinical and radiological suspicion of sarcoma, repeated bone biopsies were performed. All the biopsies revealed mature lamellar bone, normocellular marrow with moderate mixed inflammation, and fibrosis, indicative of a chronic inflammatory process. Given the discordance between the clinical, radiological, and pathological findings, surgical management was withheld and the patient was closely monitored. Over the course of several months, her symptoms gradually improved without any medical or surgical interventions. A follow-up X-ray taken 3 years after the initial diagnosis showed that the lesion had significantly reduced in size, nearly returning to a normal bone contour.

Chronic recurrent multifocal osteomyelitis in pediatric patients: A Chinese single center observational study and literature review

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare autoinflammatory disorder that commonly poses diagnostic challenges due to its atypical symptomatology. This observational study aimed to investigate the clinical features, laboratory test results, imaging features, and treatment strategies for pediatric patients with CRMO. We retrospectively analyzed 7 pediatric patients with CRMO treated at the Department of Pediatric Orthopedics, First Affiliated Hospital of Guangzhou University of Chinese Medicine between January 2018 and February 2022. This study aimed to enhance current understanding of CRMO by exploring in-depth clinical data. The study cohort comprised 5 males and 2 females, aged 3 to 13 years. All patients experienced symptoms for a median duration of 6 months prior to hospitalization, at which point they presented with recurrent pain and various accompanying signs including hypothermia (14.28%), swelling (42.85%), localized skin warmth (42.85%), and plantar pustules (14.28%). The femurs (71.42%) and tibia (71.42%) were frequently affected. Radiographic and computed tomography scans revealed osteosclerosis and osteolytic lesions, while magnetic resonance imaging revealed bone marrow edema. Histological examination of bone biopsies from 4 patients revealed fibrous tissue hyperplasia and lymphocytic and neutrophilic infiltration, despite negative bacterial cultures. Laboratory test results were either normal or slightly elevated. Symptomatic improvement was observed in 6 patients (85.72%) treated with nonsteroidal anti-inflammatory drugs, while 1 patient (14.28%) resistant to nonsteroidal anti-inflammatory drugs responded well to tumor necrosis factor inhibitors. The clinical presentation of CRMO lacks specificity, with unexplained bone pain being the most common symptom. Precise diagnosis and timely intervention depend on a thorough magnetic resonance imaging evaluation for lesion detection, which facilitates CRMO diagnosis. This study offers valuable insights into the clinical manifestations, laboratory findings, imaging features, and treatment strategies of CRMO in pediatric patients.

A rare adult presentation of chronic recurrent multifocal osteomyelitis (CRMO) in 38-year female with exclusive spinal involvement

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare, autoinflammatory bone disorder most often seen in children and adolescents characterized by recurrent episodes of sterile osteolytic osseous lesions. Diagnosing CRMO requires the exclusion of other conditions, which is often challenging due to its varied presentations and progression. However, adult-onset CRMO and exclusive spinal cases are extremely rare events, highlighting the importance of this case. Our case presents a 38-year-old female with chronic back pain for 6 months of postepidural anesthesia during a C-section. The pain was progressive, exacerbated by movement, and partially relieved by painkillers. The patient had tenderness on physical examination in the thoracolumbar region. MRI of the spine showed multiple endplate changes, and extensive laboratory tests and biopsy ruled out infectious cause and malignancy, leading to the diagnosis of CRMO. The connection between pain and epidural anesthesia was only an incidental finding. The patient was treated effectively with steroids and etanercept. CRMO is mainly a childhood disease, with adult cases being very rare. Isolated spinal involvement in CRMO is particularly rare and can make the diagnosis challenging. This case highlights that CRMO should be considered in adults with an atypical isolated spinal lesion. NSAIDs are the main treatment, with corticosteroids and TNF inhibitors used in unresponsive cases. This case underscores the need for heightened awareness of CRMO's potential to present in adults with atypical isolated spinal lesions, which could lead to more timely and accurate diagnoses.

Geriatric chronic recurrent multifocal osteomyelitis (CRMO) mimicking multifocal multiple myeloma: a first in an octogenarian

Chronic recurrent multifocal osteomyelitis (CRMO), an autoinflammatory bone disorder characterized by non-bacterial osteomyelitis causing recurrent multifocal bone lesions, is a well-known, yet uncommon pediatric condition that rarely affects adults; to date, it has never been diagnosed over the age of 75. The following report will discuss the first octogenarian diagnosed with CRMO and therefore represents an exceptionally rare presentation of a rare disease. An 83-year-old woman presented with progressive right shoulder, forearm, and hip pain, with associated weight loss and global weakness, requiring a wheelchair for mobility. Imaging revealed a pathologic right ulna fracture in addition to lytic lesions of the right proximal humerus and proximal femur. The clinical picture was thus that of a patient with probable multiple myeloma versus metastatic disease. After an extensive workup, however, the lesions were not malignant; histologic findings were instead suggestive of chronic osteomyelitis with negative cultures. Given the multifocal nature of this condition, combined with a lack of clinical symptoms of infection, a diagnosis of CRMO was rendered. The patient underwent intramedullary nailing of the right femur and splinting of the ulna, with a subsequent remarkable recovery to painless ambulation, complete union of the right ulna fracture, and resolution of the lytic lesions without receiving any targeted medical treatment. This case highlights the importance of maintaining CRMO on the differential for multifocal skeletal lesions, regardless of age. Performing a thorough workup with necessary imaging, biopsy, and culture are critical to establishing this diagnosis, which can only made as a diagnosis of exclusion.

Chronic nonbacterial osteomyelitis in neuroradiology - behavior and evolution of vertebral and mandibular lesions on imaging

BACKGROUND

Chronic nonbacterial osteomyelitis (CNO) is a rare non-infectious inflammatory musculoskeletal disease where imaging plays a key diagnostic role. Vertebral and mandibular lesions are frequent manifestations, meaning their awareness is crucial for the neuroradiologist to avoid delays in diagnosis and treatment.

OBJECTIVE

Characterize vertebral and mandibular CNO lesions on imaging to assist practicing neuroradiologists in better identifying this disease.

MATERIALS AND METHODS

Retrospective review of all CNO patients of our pediatric center, including only patients with vertebral or mandibular lesions. All imaging exams were analyzed to record lesion characteristics.

RESULTS

We included 13 patients (six male). The mean age of onset was 12.3 years. Ten patients had only vertebral lesions, two had only mandibular lesions, and one had both. For patients with vertebral lesions, the median number of levels affected was three, 81.8% had multiple levels affected, 90.0% had dorsal spine lesions, 72.7% had platyspondyly, and 81.8% had inflammatory changes. All vertebral lesions had at least partial resolution of inflammatory findings, the mean time of lesion activity was 2.5 years, and recurrence occurred in 27.3%. Three patients had sacral lesions, all with sacroiliitis. In patients with mandibular lesions, all had unilateral lesions involving the mandibular ramus, all had hyperostosis, periosteal reaction, bone edema, and soft tissue inflammation, all had partial resolution on follow-up, and one had recurrence.

CONCLUSION

CNO vertebral lesions are not rare, are often multiple, predominantly affect dorsal levels, and most result in vertebral height loss. Resolution of vertebral inflammatory lesions is frequent, but so is recurrence. Sacral lesions may be present and result in sacroiliitis. The mandible may be a site of unifocal disease, typically affecting the ramus, with prominent bony changes and soft tissue inflammation.

Current and future advances in practice: SAPHO syndrome and chronic non-bacterial osteitis (CNO)

Synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome is a rare, underdiagnosed disease with a wide clinical spectrum. Sterile bone inflammation, predominantly of the anterior chest, and skin manifestations (palmoplantar pustulosis, psoriasis vulgaris and acne) are the key features of SAPHO, which shares certain similarities with SpA. SAPHO is closely related to paediatric chronic non-bacterial osteitis (CNO), a spectrum of autoinflammatory bone diseases. The aetiology of SAPHO is considered multifactorial based on a complex interplay of genetic, immune and infectious factors. Despite the increasing awareness of SAPHO/CNO, diagnostic delay is common, as validated classification and diagnostic criteria are lacking. Treatment of SAPHO represents a challenge and includes anti-inflammatory drugs, antibiotics, bisphosphonates, synthetic conventional DMARDs and off-label use of anti-cytokine biologics and Janus kinase inhibitors. This review summarizes the current diagnostic and practical treatment approach to SAPHO/CNO and highlights the ongoing research endeavours concerning the definition and validation of diagnostic criteria, core domains and treatment.

Spine Involvement and Vertebral Deformity in Patients Diagnosed with Chronic Recurrent Multifocal Osteomyelitis

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory disorder of bone, typically arising adjacent to the physes of long bones but also seen throughout the skeleton. For patients with spinal involvement, CRMO lesions can cause compression deformities with a range of severity from minimal anterior wedging to circumferential height loss, known as vertebra plana. This study examines a large cohort of CRMO patients to determine the prevalence of spine involvement and vertebral deformity.

METHODS

This is a retrospective review of all patients with a diagnosis of CRMO seen at our institution between January 2003 and December 2020. These patients were identified through a prospectively maintained database of all CRMO patients seen at the institution. A retrospective review was undertaken to identify all patients with spinal involvement and determine the prevalence of CRMO in the spine and its effects on vertebral height and deformity.

RESULTS

Of 170 patients included in this study, 48 (28.2%) were found to have spinal involvement. Among patients with spinal involvement, vertebral body lesions were identified in 27 (56.3%) patients. The remaining lesions were in the sacrum or posterior elements. Radiographic evidence of the vertebral body height loss was noted in 23 of these 27 patients.

CONCLUSIONS

This cohort of CRMO patients demonstrates that 28% of patients have spinal involvement, and 48% of those patients have vertebral body height loss. While the ideal treatment for spinal CRMO has yet to be determined, imaging studies, including whole-body MRI and spine-specific MRI, are useful in identifying vertebral lesions and deformities. Identification and surveillance of these lesions are important as the disorder has a relapsing and remitting course, and patients can develop significant vertebral body height loss. Once deformity has developed, we have seen no evidence of reconstitution of the height of the collapsed vertebra. Bisphosphonates have been successful in preventing the progression of vertebral body height loss.

LEVEL OF EVIDENCE

Level II: Retrospective study investigating spinal involvement and prevalence of vertebral body deformity in patients diagnosed with CRMO.

Extra-osseous manifestations in chronic recurrent multifocal osteomyelitis: a retrospective study

OBJECTIVES

Extra-osseous (EO) manifestations are poorly characterized in chronic recurrent multifocal osteomyelitis (CRMO). This study aimed to further define the frequency, characteristics and treatment of EO events in CRMO and whether different phenotypes can be distinguished and benefit from special management.

METHODS

This multicentre retrospective study included CRMO patients followed in several paediatric rheumatology departments in France between 2015 and 2022. EO manifestations were defined as skin lesions, gastrointestinal manifestations, arthritis, enthesitis, sacroiliitis, uveitis, vasculitis and fever. At the last visit, the physician defined CRMO as active in the presence of clinical manifestations including both osseous and EO symptoms.

RESULTS

We included 133 patients; 87 (65.4%) were girls and the median age at first symptoms was 9.0 years (interquartile range 7.0-10.0). EO manifestations were described in 90 (67.7%) patients, with a predominance of skin lesions [n = 51/90 (56.7%)], followed by sacroiliitis [n = 38/90 (42.2%)], enthesitis [n = 21/90 (23.3%)], arthritis [n = 14/90 (15.6%)] and gastrointestinal manifestations [n = 6/90 (6.7%)]. The use of non-steroidal anti-inflammatory drugs and bisphosphonates did not differ by the presence or not of EO manifestations. Biologics were taken more frequently by patients with than without EO manifestations (P < 0.001); TNF inhibitors were used in 33 (36.7%) EO-positive patients. Under this treatment, 18 (54.5%) patients achieved complete remission of osseous and EO manifestations. At the last visit, more EO+ than EO- patients were on treatment (P = 0.009), with active disease in 58 (64.4%) patients.

CONCLUSION

The analysis of EO manifestations in CRMO delineates two groups of patients in terms of severity and treatments used. Our study opens up new pathophysiological leads that may underlie the wide range of CRMO phenotypes.

Fluorodeoxyglucose Positron Emission Tomography Evaluation of Chronic Recurrent Multifocal Osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease that predominantly affects children and adolescents. Currently, CRMO diagnoses are based on a combination of clinical, radiological, pathological, and longitudinal findings. However, distinguishing CRMO from malignant bone tumors using imaging is occasionally challenging. Fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging characteristics in CRMO (specifically, the maximum standardized uptake value (SUVmax)) have been described previously. The lesions exhibited increased FDG uptake despite the benign nature of the disease; the SUVmax was notably high (4.90). These findings suggest that FDG/PET plays a limited role in the differential diagnosis of CRMO.

Chronic non-bacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO) with a focus on pamidronate therapy

Chronic recurrent multifocal osteomyelitis (CRMO), also called chronic nonbacterial osteomyelitis (CNO) or nonbacterial osteomyelitis (NBO), is a rare autoinflammatory bone disease of unknown etiology. However, the number of patients properly diagnosed would increase with better knowledge of the disease. In this regard, whole-body magnetic resonance imaging (WB MRI) has been found to be a better predictor of active lesions than clinical examination. Importantly, the RINBO index (radiologic index for NBO) quantifies the involvement based on the WB MRI. Further, a chronic nonbacterial osteomyelitis MRI scoring (CROMRIS) has been developed as an online tool for assessing WB MRI. The therapy consists of non-steroidal anti-inflammatory drugs (NSAIDs), bisphosphonates (pamidronate, zoledronate, etc.) and other drugs, including biologics. Pamidronate is an appropriate and safe therapy. The first pilot prospective randomised controlled trial (RCT) on pamidronate vs. placebo was carried out in adults. No RCT has been done in children yet. Besides RCTs, there are a number of issues to be explored in future, i.e. predictors of therapy effect, optimal therapy duration, predictors of therapy discontinuation and evaluation of optimal therapy protocol. Recently, the CNO clinical disease activity score (CDAS) was constructed and validated but the classification criteria are still being developed. As collaboration on this rare disease is essential, a prospective Chronic Nonbacterial Osteomyelitis International Registry (CHOIR) was established to generate future comparative effectiveness research data.

Preferential involvement of the pelvis and hips along with active sacroiliitis in chronic nonbacterial osteomyelitis: MRI of 97 patients from a single tertiary referral center

OBJECTIVE

To present MRI distribution of active osteitis in a single tertiary referral center cohort of patients with chronic nonbacterial osteomyelitis (CNO).

METHODS

Two musculoskeletal radiologists retrospectively reviewed MRI examinations of all patients with a final clinical diagnosis of CNO over 15 years. Sites of active osteitis at any time during the course of disease were divided into seven groups: (A) mandible, sternum, clavicles, or scapulas; (B) upper extremities; (C) subchondral sacrum and ilium immediately subjacent to sacroiliac joints (active osteitis denoting "active sacroiliitis" here); (D) pelvis and proximal 1/3 of femurs (excluding group C); (E) bones surrounding knees including distal 2/3 of femurs and 1/2 of proximal tibias and fibulas; (F) distal legs (including distal 1/2 of tibias and fibulas), ankles, or feet; (G) spine (excluding group C). Temporal changes of lesions in response to treatment (or other treatment-related changes such as pamidronate lines) were not within the scope of the study.

RESULTS

Among 97 CNO patients (53 males [55%], 44 females; age at onset, mean ± SD, 8.5 ± 3.2 years; age at diagnosis, 10.3 ± 3.3 years), whole-body (WB) MRI was performed in 92%, mostly following an initial targeted MRI (94%). A total of 557 (346 targeted and 211 WB) MRIs were analyzed. Biopsy was obtained in 39 patients (40%), all consistent with CNO or featuring supporting findings. The most common locations for active osteitis were groups D (78%; 95% CI 69‒85%) and C (72%; 95% CI 62‒80%).

CONCLUSION

Pelvis and hips were preferentially involved in this cohort of CNO patients along with a marked presence of active sacroiliitis.

CLINICAL RELEVANCE STATEMENT

When suggestive findings of CNO are identified elsewhere in the body, the next targeted site of MRI should be the pelvis (entirely including sacroiliac joints) and hips, if whole-body MRI is not available or feasible.

KEY POINTS

• Heavy reliance on MRI for diagnosis of CNO underscores the importance of suggestive distribution patterns. • Pelvis and hips are the most common (78%) sites of CNO involvement along with active sacroiliitis (72%). • Pelvis including sacroiliac joints and hips should be targeted on MRI when CNO is suspected.

Chronic recurrent multifocal osteomyelitis: Case report and review of the literature

BACKGROUNDS

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare inflammatory disease.

OBJECTIVE

This report aims to analyze the clinical characteristics of CRMO and enhance clinicians' comprehension. We present 3 atypical cases, highlighting their unique clinical features, diagnostic challenges, and effective treatment strategies.

METHODS

We retrieved 3 CRMO cases in our hospital from September 2019 to August 2022. The clinical features were analyzed retrospectively, and relevant literatures were reviewed.

RESULTS

All 3 cases initially presented with bone pain, normal leucocyte counts, negative rheumatoid factors and no signs of sclerotic or hyperostotic lesions. Case 1, a 12-year-old girl, exhibited concurrent acne on the forehead and historic necrotizing lymphadenitis, a previously unreported association with CRMO. Case 2, a 14-year-old boy, tested positive for human leukocyte antigen-B27 and displayed scoliosis along with multifocal osteomyelitis. Case 3, a 9-year-old girl, presented with scoliosis, and chest computed tomography revealed changes in the T8 vertebral body, initially suggesting Langerhans cell histiocytosis. Bone biopsy was conducted in case 1 and case 3, revealing chronic inflammation. All 3 cases affected long bones, pelvis, and vertebra, involving 8, 6 and 5 bones, respectively, identified by magnetic resonance imaging. Genetic analysis was undertaken in cases 1 and 2 but no pathogenic mutations were identified. Upon the confirmation of a CRMO diagnosis, all patients were initiated on a treatment regimen comprising nonsteroidal anti-inflammatory drugs and tumor necrosis factor-α inhibitors. In cases 1 and 2, due to the severity of their bone pain, they were also administered to disease-modifying anti-rheumatic drugs, specifically methotrexate. All 3 patients achieved remission of bone pain. To gain a more comprehensive understanding of CRMO, we conducted a thorough review of relevant literature.

CONCLUSION

CRMO is a rare autoinflammatory bone disorder with diverse clinical presentations and a lack of specific laboratory tests, which leads to potency to misdiagnosis or delayed diagnosis. By raising awareness and improving diagnostic criteria, physicians are now better equipped to identify CRMO. We contribute to share our understanding of CRMO by presenting 3 cases with untypical clinical features, highlighting the importance of recognizing this rare condition for timely and effective management.

Musculoskeletal symptoms and their impact on health-related quality of life in chronic nonbacterial osteomyelitis patients

INTRODUCTION

Chronic non-bacterial osteomyelitis (CNO) is a rare, non-infection- related inflammatory disorder that affects children and teens. Clinical manifestations of CNO range widely from moderate, time-limited, monofocal inflammation of the bone to extreme multifocal or chronically active inflammation of the bone.

OBJECTIVES

The main aim of this study was to explore the correlation between musculoskeletal (MSK) symptoms and health-related quality of life (HRQoL) in patients with CNO.

METHODS

Children and adults with CNO and their parents were asked to answer a web-based survey. The survey consisted of multiple questions centered around demographic, clinical and therapeutic data, MSK discomfort form based on the Nordic MSK Questionnaire and HRQoL based on Pediatric Quality of Life Inventory-4 (PedsQL-4) and PedsQL rheumatology module. The inclusion criteria included diagnosis of CNO before the age of 18. Patients who had malignancies or any chronic rheumatic, MSK, neurological disease prior to CNO onset were excluded.

RESULTS

There was a total of 68 participants, mostly females (66.2%), with median age 14 years and median disease duration 4.75 years. The median number of bones affected by CNO was 5 and ranged from 1 to 24 bones. Among the studied patients, 45 patients (66.2%) had MSK manifestations at the last month. The most commonly affected part was ankle and feet (26.5%). Regarding HRQoL, patients with MSK manifestations had lower scores than did patients without in PedsQL-4 (p < 0.001) including domains of physical functioning (p < 0.001), emotional functioning (p = 0.033), social functioning (p < 0.001) and school functioning (p = 0.007) in addition to lower scores in PedsQL rheumatology module (p < 0.001) including domains of pain and hurt (p < 0.001), daily activities (p < 0.001), treatment (p = 0.035), worry (p = 0.001) and communication (p < 0.001).

CONCLUSION

MSK manifestations have a negative impact on HRQoL in CNO patients. So, early identification and treatment are highly recommended.

Chronic non-bacterial osteomyelitis (CNO) in childhood and adolescence - a disease with many faces

BACKGROUND

Chronic non-bacterial osteomyelitis (CNO) is a chronic inflammatory skeletal disease that affects particularly children and adolescents and is often diagnosed with a delay. With whole-body MRI, early diagnosis of this disease is possible in many cases. Since children and adolescents frequently present with non-specific complaints for outpatient radiological diagnosis, every radiologist should have basic knowledge of this complex clinical picture.

MATERIALS

In this review the basics and current findings regarding the disease are discussed. Unusual courses are also presented.

RESULTS AND CONCLUSION

With knowledge of the radiographic and MR tomographic characteristics of the mostly multifocal bone lesions, the diagnosis of CNO can be reliably made in many cases. In particular, the early use of whole-body MRI plays an important role. Thus, therapeutic delays and resulting complications and the number of unnecessary biopsies for diagnosis can be reduced.

A clinico-radiological review of chronic non-bacterial osteomyelitis in paediatrics, adolescents, and adults: demystifying a forgotten differential

Chronic non-bacterial osteomyelitis (CNO), also known as non-bacterial osteitis, is a chronic autoinflammatory disease of unknown aetiology that primarily occurs in the paediatric population, although rare cases of adult-onset disease also exist. CNO has non-specific clinical and radiological presentations, and the affected population often present with bone pain of insidious onset secondary to sterile bony inflammation that can be associated with swelling, focal tenderness, and warmth at the affected sites. The pattern of bony involvement appears to be dependent on the age of onset, with adults frequently having axial skeletal lesions and children and adolescents often being affected in the appendicular skeletal sites. CNO is a diagnosis of exclusion, and imaging is heavily relied on to identify and characterise the bony lesions in addition to exclude diseases that can mimic CNO. Magnetic resonance imaging is often the reference standard with biochemical and histopathological findings being complementary. Although combining imaging methods can be used to facilitate the diagnosis, a single technique could be adequate depending on the clinical picture. Given the relatively rare incidence of CNO, limited awareness of the disease among care providers, and its similarity in clinical and radiological presentation to various bony diseases, there are often long delays in diagnosis, with adults being unfavourably affected compared to paediatrics and adolescents. This review of CNO will describe the condition, overview its clinical presentation, highlight the radiological features, and emphasise clinical pearls that can aid in diagnosis and ruling out the mimics.

Pediatric mandibular chronic nonbacterial osteomyelitis: A case report with 12 years of radiologic follow-up

Chronic nonbacterial osteomyelitis (CNO) is histologically characterized by nonspecific osteitis. This inflammatory disorder, which lacks an infectious origin, typically presents with chronic pain and swelling at the affected site that can persist for months or even years. However, it is rare for CNO to affect the mandible. A 10-year-old girl presented with a primary complaint of pain in her left mandible. She had no significant medical or dental history. On examination, swelling was visible on the left buccal side, and imaging revealed radiolucent bone deterioration within the left mandible. This case report presents the radiological changes observed over a 12-year follow-up period. Variations in radiopacity, radiolucency, and periosteal reactions were noted periodically. This case highlights the radiological characteristics and findings that are crucial for the diagnosis of CNO, a condition for which no clear diagnostic criteria are currently available.

Adult-onset chronic recurrent multifocal osteomyelitis: a case report

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease predominantly affecting the metaphyses of long bones and is usually seen in children. Although CRMO is generally a pediatric disease, it may also occur in adults. This may result in a delay in the diagnosis of adult-onset CRMO. This report presents an adult-onset female patient who presented with left leg pain followed by swelling in the right knee. The patient was initially started on colchicine treatment, but, due to unresponsiveness in the follow-up the patient, the treatment was switched to a combination of methotrexate and prednisolone. A satisfactory clinical recovery was achieved with these drugs. CRMO could be considered in the differential diagnosis of patients presenting with bone pain and joint complaints. Considering that the disease progresses with clinical flare-ups and remission periods, it should be kept in mind that patients should be followed closely and treatment can be changed.

Chronic Nonbacterial Osteomyelitis Associated With Familial Mediterranean Fever in Children

OBJECTIVE

Chronic nonbacterial osteomyelitis (CNO) is a noninfectious autoinflammatory bone condition that frequently occurs alongside other inflammatory diseases, such as familial Mediterranean fever (FMF). We aimed to determine the demographic, clinical, laboratory, and radiological characteristics of patients diagnosed with both FMF and CNO.

METHODS

We reviewed the medical records of pediatric patients with both CNO and FMF at 3 pediatric rheumatology centers in Turkey from December 2008 to 2022. Patients' demographics, laboratory features, imaging findings, and treatment were recorded.

RESULTS

Twelve patients with FMF and CNO were included in the study. Half of them were female. The mean ages at onset for FMF and CNO symptoms were 80 and 116 months, whereas the ages at diagnosis for FMF and CNO were 100 and 125 months, respectively. Ten patients (83.3%) had M694V mutation on at least 1 allele of the Mediterranean fever (MEFV) gene. The most common sites of osteitis were the long bones (58.3%), pelvis (50%), and clavicles (25%). Ten patients (83%) received nonsteroidal anti-inflammatory drugs; 8 (66%) received disease-modifying antirheumatic drugs; biological therapy was administered to 5 patients (41%), who did not respond to these treatments; and all patients received colchicine.

CONCLUSION

The increased frequency of FMF in patients with CNO is of interest. Because most patients with CNO and FMF carried a homozygous or combined heterozygous M694V mutation, we speculated that the M694V mutation may play a role in the development of osteitis. Further studies are needed to elucidate the link between FMF and CNO.

Chronic Recurrent Multifocal Osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is an underrecognized autoinflammatory disease affecting the skeletal system. Its vague symptoms are often first attributed to growing pains, infection, or malignancy, which can lead to a delay in diagnosis for days to years. Untreated CRMO has the potential to cause debilitating skeletal deformities, arthritis, and chronic pain; hence early recognition and treatment are paramount. MRI is the gold standard for diagnosis. Treatment consists of various antiinflammatory medications and may also include bisphosphonates if vulnerable skeletal sites are involved. Even when treated, the disease may have a relapsing course lasting years.

Chronic Nonbacterial Osteomyelitis in Inflammatory Bowel Disease

Chronic nonbacterial osteomyelitis (CNO), also known as chronic recurrent multifocal osteomyelitis (CRMO), is a rare autoinflammatory bone disease primarily affecting children and adolescents. This review presents a comprehensive analysis of the intricate relationship between CNO and inflammatory bowel disease (IBD), shedding light on shared pathophysiological mechanisms and clinical management. A thorough literature review was conducted, encompassing 24 case reports involving 40 patients. The demographic distribution of patients revealed a near-equal gender ratio, with a median age of diagnosis at 12 years. The diagnosis patterns showed a higher proportion of CNO as the initial diagnosis, while Crohn's disease was more prevalent than ulcerative colitis. The time interval between the clinical presentations varied, ranging from simultaneous detection to a substantial 15-year gap. Treatment modalities included nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, aminosalicylates, and biologic agents, such as infliximab, often overlapping in their use and suggesting shared pathophysiological pathways. Both conditions displayed systemic manifestations, and patients often responded well to immunosuppressive medications. The pathophysiology of CNO involves a genetic predisposition, cytokine dysregulation, and osteoclast activation. Dysregulated innate immunity results in immune cell infiltration into bones, causing sterile bone lesions. Notably, emerging evidence hints at a potential link between the microbiome and CNO. In contrast, IBD results from imbalanced mucosal immune responses to the intestinal microbiota. Polymorphisms in the promotor region of IL-10, common cytokines, immune cells, and genetic markers indicate shared immunological and genetic factors between CNO and IBD. Both conditions also involve extraintestinal symptoms. This analysis underscores the need for clinical awareness of the co-occurrence of CNO and IBD, especially among pediatric patients. A deepened understanding of the connections between these seemingly distinct diseases could lead to more effective management and improved patient outcomes.

Skin manifestations help identifying different phenotypes of paediatric SAPHO syndrome

OBJECTIVES

to evaluate whether the heterogeneous skin manifestations might influence the disease presentation and outcome of a cohort of SAPHO children.

METHODS

the clinical, serological, imaging and therapeutic data of 14 SAPHO patients, followed between 2001 and 2022 at the Unit for Autoinflammatory diseases at the Gaslini Hospital, were reviewed. According to their cutaneous manifestations, patients were divided into 2 groups: the acne-hidradenitis suppurativa (HS) and the Palmo-Plantar Pustulosis (PPP) group. Data were retrieved from the Eurofever database.

RESULTS

all patients presented bone involvement characterized by Chronic Recurrent multifocal Osteomyelitis (CRMO): 8 patients presented acne-HS while 6 patients had PPP. In the PPP group, all patients were female, characterized by a prepuberal disease onset with osteoarticular manifestations, followed by the appearance of PPP in the following 6 months. This group responded well to the treatments. In the acne-HS group, 7/8 patients were male: the disease onset was characterized by skin manifestations in pubertal age, followed by osteoarticular manifestations in the following year. This group presented a severe refractory skin disease that required in most cases the addition of biological therapies. A literature review confirmed our data highlighting the association males-acne-puberal age and female-PPP-prepuberal age.

CONCLUSION

paediatric SAPHO patients should be mainly stratified according to their skin involvement. In fact, our data suggest that two different skin phenotypes may be identified in SAPHO: the first is constituted by prepuberal females with PPP and a prevalent osteoarticular involvement, while the second by puberal males with a difficult-to-treat acne-HS.

Long-term follow-up of children with chronic non-bacterial osteomyelitis-assessment of disease activity, risk factors, and outcome

INTRODUCTION

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone-disease of unknown origin. The National Pediatric Rheumatologic Database (NPRD) collects long-term data of children and adolescents with rheumatic diseases including CNO.

OBJECTIVE

To assess characteristics, courses, and outcomes of CNO with onset in childhood and adolescence and to identify outcome predictors.

METHODS

From 2015 to 2021 patients with a confirmed diagnosis of CNO, who were registered in the NPRD during their first year of disease and at least one follow-up visit, were included in this analysis and observed for up to 4 years.

RESULTS

Four hundred patients with recent diagnosis of CNO were enrolled in the NRPD during the study period. After 4 years, patient data documentation was sufficient to be analyzed in 81 patients. A significant decline of clinical and radiological lesions is reported: at inclusion in the registry, the mean number of clinical lesions was 2.0 and 3.0 MRI lesions per patient. A significant decrease of manifestations during 4 years of follow-up (mean clinical lesions 0.5, p < 0.001; mean MRI lesions 0.9 (p < 0.001)) was documented. A significant improvement of physician global disease activity (PGDA), patient-reported overall well-being, and childhood health assessment questionnaire (C-HAQ) was documented. Therapeutically, an increase of disease-modifying anti-rheumatic drugs over the years can be stated, while bisphosphonates rather seem to be considered as a therapeutic DMARD option in the first years of disease. Only 5-7% of the patients had a severe disease course as defined by a PGDA >  = 4. Predictors associated with a severe disease course include the site of inflammation (pelvis, lower extremity, clavicle), increased erythrocyte sedimentation rate, and multifocal disease at first documentation. The previously published composite PedCNO disease activity score was analyzed revealing a PedCNO70 in 55% of the patients at 4YFU.

CONCLUSION

An improvement of physician global disease activity (PGDA), patient reported overall well-being and imaging-defined disease activity measures was documented, suggesting that inactivity of CNO disease can be reached. PedCNO score and especially PGDA, MRI-defined lesions and in a number of patients also the C-HAQ seem to be reliable parameters for describing disease activity. The identification of risk factors at the beginning of the disease might influence treatment decision in the future.

Feasibility of Conducting Comparative Effectiveness Research and Validation of a Clinical Disease Activity Score for Chronic Nonbacterial Osteomyelitis

OBJECTIVE

Prospective comparative effectiveness research (CER) in chronic nonbacterial osteomyelitis (CNO) is lacking. Our objectives were to (1) determine the use and safety of each consensus treatment plan (CTP) regimen for CNO, (2) assess the feasibility of using the Chronic Nonbacterial Osteomyelitis International Registry (CHOIR) data for CER, and (3) develop and validate a CNO clinical disease activity score (CDAS) using CHOIR.

METHODS

Consenting children or young adults with CNO were enrolled into CHOIR. Demographic, clinical, and imaging data were prospectively collected. The CNO CDAS was developed through a Delphi survey and nominal group technique. External validation surveys were administered to CHOIR participants.

RESULTS

One hundred forty (78.2%) CHOIR participants enrolled between August 2018 and September 2020 received at least 1 CTP regimen. Baseline characteristics from different CTP groups were well matched. Patient pain, patient global assessment, and clinical CNO lesion count were key variables included in the CNO CDAS. The CDAS showed a strong correlation with patient/parent report of difficulty using a limb, back, or jaw and patient/parent report of disease severity, but a weak correlation with patient/parent report of fatigue, sadness, and worry. The change in CDAS was significant in patients reporting disease worsening or improvement (P < 0.001). The CDAS significantly decreased after initiating second-line treatments from median 12.0 (IQR 8.0-15.5) to 5.0 (IQR 3.0-12.0; P = 0.002). Although second-line treatments were well tolerated, psoriasis was the most common adverse event.

CONCLUSION

The CNO CDAS was developed and validated for disease monitoring and assessment of treatment effectiveness. CHOIR provided a comprehensive framework for future CER.

Update on treatment responses and outcome measure development in chronic nonbacterial osteomyelitis

PURPOSE OF REVIEW

To review recent trends in treatment and recent progress in developing outcome measures needed for chronic nonbacterial osteomyelitis (CNO) clinical trials.

RECENT FINDINGS

CNO is an autoinflammatory bone disease. In a minority of patients, the disease is genetically driven, and diagnosis can be made by DNA sequencing. However, for nonsyndromic CNO there is no diagnostic test. The number of children with CNO appears to be increasing and damage is common. Increases in CNO diagnosis is due to raised awareness, increased availability of whole-body magnetic resonance imaging and rising incidence. Treatment remains empiric and it is unclear which second line treatment is superior. Tumor necrosis factor inhibitors (TNFi) and bisphosphonates continue to be used as second line agents for nonsteroidal anti-inflammatory drugs (NSAID) refractory CNO; newer immune modulatory medications are used if this fails. Validated classification criteria, clinical outcome measures and imaging scoring standards are needed for successful clinical trials.

SUMMARY

Best treatment for NSAID refractory CNO remains unclear. Classification criteria, clinical outcomes measures and standardized imaging scoring have been developed or are near completion. This will facilitate robust clinical trials in CNO with the goal of having approved medications for this painful disease.

Golimumab in Children with Chronic Recurrent Multifocal Osteomyelitis: A Case Series and Review of the Literature

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare autoinflammatory bone disease requiring immunosuppressive treatment in half of patients. Monoclonal tumor necrosis factor inhibitors (TNFi) are often used as effective second-line off-label therapies. However, paradoxical psoriasis can occur in a subset of patients exposed to monoclonal TNFi and can prompt conversion to alternate therapy if severe.

OBJECTIVE

The aim of this study was to determine the efficacy and safety of golimumab, a fully humanized TNFi, in children with CRMO, including those who develop paradoxical psoriasis after exposure to other monoclonal TNFi.

METHODS

A retrospective chart review was conducted of patients with CRMO who received golimumab in a single center between 01 June, 2018 and 31 December, 2020. Patients who were diagnosed before 21 years of age and followed up for CRMO at least once after receiving ≥ 3 months of golimumab were included. Extracted data included patient demographics, whole-body MRI lesion counts, clinically relevant data, laboratory results, patient-reported outcomes, and psoriasis burden. Linear mixed models with log-transformed outcomes were used to assess changes in the outcomes over time. The random effect is included in the model to account for the within-subject correlation of repeated measures. p-values and 95% confidence intervals were reported.

RESULTS

Eighteen patients were included. Patients were observed for a median of 9.95 months [interquartile range 3.84-15.64]. The median age at the initiation of golimumab was 10.95 years [9.86-13.77] and the median duration of disease between the disease onset and the initiation of golimumab was 2.60 years [1.66-3.62]. Ten patients received golimumab via intravenous route and eight patients received golimumab via subcutaneous route. The median dose was 1.64 mg/kg/month [1.46, 2]. Fourteen patients were previously treated with disease-modifying antirheumatic drugs and 17 with other TNFi. Patients treated with golimumab showed significant improvement in median physician global assessment for CRMO from 2.00 [1.00-3.00] to 0.00 [0.00-0.25] by the fourth visit (p < 0.001), with median erythrocyte sedimentation rate (ESR) decreasing significantly from 12.00 [6.75-23.75] to 5.00 [3.00-10.00] by the fourth visit (p < 0.05). The median number of lesions on MRI decreased significantly from 3.50 [2.00-5.50] to 0.50 [0.00-4.25] lesions per patient (p < 0.01). Nine out of 12 patients who had previous paradoxical psoriasis associated with adalimumab or infliximab had persistent active psoriasis at study baseline. For patients with psoriasis at study baseline, the prevalence of psoriasis had decreased from 100% to approximately 50-57% at the following visits. Of the 18 patients initiated on golimumab in this study, there was only one new case of mild psoriasis in a patient with previously resolved infliximab-associated paradoxical psoriasis. No serious infections or adverse events were noted during the study. Two patients in the study showed clinical improvement with concomitant golimumab and ustekinumab with no reported adverse side effects or increased effects in these patients over a 16-month interval, showing that this combination can be safe and effective for children with CRMO.

CONCLUSION

In our experience, golimumab has been shown to be a safe and effective therapy for CRMO and demonstrated improvement in paradoxical psoriasis in many patients. Longer follow-up periods would be helpful to develop longer term outcomes data for patients with CRMO and overall paradoxical psoriasis risk.

Classification and management strategies for paediatric chronic nonbacterial osteomyelitis and chronic recurrent multifocal osteomyelitis

INTRODUCTION

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disease that most commonly affects children and adolescents causing significant pain and damage to bones. The absence of diagnostic criteria and biomarkers, an incomplete understanding of the molecular pathophysiology, and lack of evidence from randomized and controlled trials make the diagnosis and care challenging.

AREAS COVERED

This review provides an overview of the clinical and epidemiological features of CNO and displays diagnostic challenges and how they can be addressed following strategies used internationally and by the authors. It summarizes the molecular pathophysiology, including pathological activation of the NLRP3 inflammasome and IL-1 secretion, and how these observations can inform future treatment strategies. Finally, it provides a summary of ongoing initiatives aiming at classification criteria (ACR/EULAR) and outcome measures (OMERACT) that will enable the generation of evidence through clinical trials.

EXPERT OPINION

Scientific efforts have linked molecular mechanisms to cytokine dysregulation in CNO, thereby delivering arguments for cytokine blocking strategies. Recent and ongoing collaborative international efforts are providing the basis to move toward clinical trials and target directed treatments for CNO that find approval by regulatory agencies.

Priorities in Chronic nonbacterial osteomyelitis (CNO) - results from an international survey and roundtable discussions

OBJECTIVE

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder that predominantly affects children and young people. The pathophysiology and molecular mechanisms of CNO remain poorly understood, and diagnostic criteria and biomarkers are lacking. As a result, treatment is empiric and follows personal experience, case series and expert consensus plans.

METHODS

A survey was designed to gain insight on clinician and patient experiences of diagnosing and treating CNO and to collate opinions on research priorities. A version containing 24 questions was circulated among international expert clinicians and clinical academics (27 contacted, 21 responses). An equivalent questionnaire containing 20 questions was shared to explore the experience and priorities of CNO patients and family members (93 responses).

RESULTS

Responses were used to select topics for four moderated roundtable discussions at the "International Conference on CNO and autoinflammatory bone disease" (Liverpool, United Kingdom, May 25-26^th, 2022). The group identified deciphering the pathophysiology of CNO to be the highest priority, followed by clinical trials, necessary outcome measures and classification criteria. Surprisingly, mental wellbeing scored behind these items.

CONCLUSIONS

Agreement exists among clinicians, academics, patients and families that deciphering the pathophysiology of CNO is of highest priority to inform clinical trials that will allow for the approval of medications for the treatment of CNO by regulatory agencies.

Pediatric autoinflammatory bone disorders-a mini review with special focus on pathogenesis and inborn errors of immunity

Autoinflammatory bone disorders are a group of diseases characterized by sterile osteomyelitis. This includes chronic nonbacterial osteomyelitis and the monogenic forms, Majeed syndrome and deficiency of the interleukin-1 receptor antagonist. These disorders result from innate immune system dysregulation and cytokine imbalance that triggers inflammasome activation causing downstream osteoclastogenesis and excessive bone remodeling. In this review, we will summarize the immunopathogenesis of pediatric autoinflammatory bone diseases with a special focus on the genetics and inborn errors of immunity, while briefly touching on the clinical manifestations and management of each disease as well as areas for future research.

HLA-B*27 is associated with CNO in a European cohort

OBJECTIVES

To determine the influence of HLA-B27 positivity on risk of developing chronic nonbacterial osteomyelitis (CNO).

METHODS

HLA-B*27 genotype was assessed in 3 European CNO populations and compared with local control populations (572 cases, 33,256 controls). Regional or whole-body MRI was performed at diagnosis and follow-up in all cases which reduces the risk of disease misclassification. Genotyping was performed using either next generation DNA sequencing or PCR based molecular typing. Statistical analysis used Fisher's exact test with Bonferroni correction and a fixed effects model for meta-analysis of odds ratios.

RESULTS

HLA-B*27 frequency was higher in all 3 populations compared with local controls (combined odds ratio (OR) = 2.2, p-value = 3 × 10^-11). This association was much stronger in male compared with female cases (OR = 1.99, corrected p-value = 0.015). However, the HLA-B*27 status was not statistically significantly associated with co-occurrence of psoriasis, arthritis or inflammatory bowel disease.

CONCLUSION

Carriage of HLA-B*27 is associated with greater risk of developing CNO, particularly in male cases.

Transcriptome analysis based on machine learning reveals a role for autoinflammatory genes of chronic nonbacterial osteomyelitis (CNO)

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder. The origin and development of CNO involve many complex immune processes, resulting in delayed diagnosis and a lack of effective treatment. Although bioinformatics analysis has been utilized to seek key genes and pathways in CNO, only a few bioinformatics studies that focus on CNO pathogenesis and mechanisms have been reported. This study aimed to identify key biomarkers that could serve as early diagnostic or therapeutic markers for CNO. Two RNA-seq datasets (GSE133378 and GSE187429) were obtained from the Gene Expression Omnibus (GEO). Weighted gene coexpression network analysis (WGCNA) and differentially expressed gene (DEG) analysis were conducted to identify the genes associated with CNO. Then, the autoinflammatory genes most associated with CNO were identified based on the GeneCards database and a CNO prediction model, which was created by the LASSO machine learning algorithm. The accuracy of the model and effects of the autoinflammatory genes according to receiver operating characteristic (ROC) curves were verified in external datasets (GSE7014). Finally, we performed clustering analysis with ConsensusClusterPlus. In total, eighty CNO-related genes were identified and were significantly enriched in the biological processes regulation of actin filament organization, cell-cell junction organization and gamma-catenin binding. The main enriched pathways were adherens junctions, viral carcinogenesis and systemic lupus erythematosus. Two autoinflammatory genes with high expression in CNO samples were identified by combining an optimal machine learning algorithm (LASSO) with the GeneCards database. An external validation dataset (GSE187429) was utilized for ROC analysis of the prediction model and two genes, and the results indicated good efficiency. Then, based on consensus clustering analysis, we found that the expression of UTS2 and MPO differed between clusters. Finally, the ceRNA network of lncRNAs and the small molecule compounds targeting the two autoinflammatory genes were predicted. The identification of two autoinflammatory genes, the HCG18/has-mir-147a/UTS2/MPO axis and signalling pathways in this study can help us understand the molecular mechanism of CNO formation and provides candidate targets for the diagnosis and treatment of CNO.

Case Presentation of a Nine-Year-Old Female With Chronic Recurrent Multifocal Osteomyelitis

Multifocal bone pain in a pediatric patient prompts a broad differential diagnosis, which should include chronic recurrent multifocal osteomyelitis (CRMO), particularly when the patient has a personal or family history of autoimmune diseases or chronic inflammatory disorders. CRMO is a difficult diagnosis, as several similar disorders must be ruled out first, and it requires extensive verification based on clinical, radiological, and pathological criteria. It often mimics other medical diagnoses, including Langerhans cell histiocytosis and infectious osteomyelitis. Maintaining a high index of suspicion for CRMO is important to minimize unnecessary medical testing, optimize pain control, and preserve physical function. We present the case of a nine-year-old female who presented with multifocal bone pain and was diagnosed with CRMO.

Chronic Nonbacterial Osteomyelitis and Inflammatory Bowel Disease: A Literature Review-Based Cohort

Background: Chronic nonbacterial osteomyelitis (CNO) is a rare autoinflammatory bone disorder that mainly involves children and adolescents. The association with other inflammatory disorders, such as inflammatory bowel disease (IBD), psoriasis, and arthritis, has been reported in the literature. In particular, the relationship between bone and intestinal inflammation is still poorly understood. For this purpose, our review aims to describe the cases reported in the literature concerning this association and to compare them with data from our single-center cohort of patients. Methods: We conducted a literature review of published cases of CNO associated with IBD. Eligible articles were identified through a Medline search in the PubMed database until December 2022. We retrospectively reviewed medical records of patients with CNO referred to G. Pini Hospital and compared them with the literature-review-based cohort. Results: Fifty-seven patients with a defined diagnosis of CNO and associated IBD were described in the literature (female 55%). The median age of onset of the disease (CNO or IBD) was 11 years. In 32/53 (60%), a diagnosis of Crohn’s disease (CD) was made, while 18 (34%) patients were classified as suffering from ulcerative colitis (UC) and 3 (6%) from undifferentiated IBD. The diagnosis of CNO preceded the diagnosis of IBD in 59% of cases; while in 24%, IBD anticipated CNO; and in 17%, the two conditions appeared simultaneously. The median time between the two events was 24 months. In our Italian cohort (n = 23 patients), no diagnosis of IBD was made. No significant differences were found when comparing clinical and demographical characteristics of the Italian vs. review-based cohort, except for a significant involvement of rachis in the Italian group. Conclusions: The correlation between autoinflammatory bone disease and intestinal inflammation should be further investigated. It is essential to promote awareness among pediatric rheumatologists and gastroenterologists about this possible association to facilitate the diagnosis and better optimize treatment.

Chronic recurrent multifocal osteomyelitis: A multidisciplinary experience of 22 pediatric cases with a mean follow-up of 27 months

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is not a well known disorder among nonpediatricians. The aim of this study is to retrospectively evaluate the clinical outcomes of twenty-two CRMO patients presenting to two referral centres.

METHODS

This retrospective study included twenty-two children (12 males, 10 females; mean age 13 years; range 7-17 years). The diagnosis was based on clinical, radiological, and pathological findings. Data were retrieved from hospital charts.

RESULTS

The mean delay in diagnosis was 26 months (range, 0-96 months). The mean follow-up after diagnosis was 27.4 months (range, 6-47 months). Symptoms included pain, limping, local swelling, morning stiffness, and fever. 18 patients had multifocal and 4 patients had unifocal disease. Bone lesions were detected with whole-body or local MRI (Magnetic Resonance Imaging). The mean number of bone lesions was 2.5 (range, 1-8). Ten cases underwent biopsy to exclude malignancy and infection. Prior to diagnosis, cast immobilization or curettage was erroneously performed in four patients. One patient suffered from vertebral compression fracture. There is no growth disturbance or deformity in any patient.

CONCLUSION

This study demonstrated that early recognition of the disease can be improved by using Bristol criteria which should be evaluated by a multidisciplinary team rather than one single specialist. In this way, the reliability of these criteria is improved and the treatment could be given earlier with decreased delay in diagnosis. This multidisciplinary approach is also important for decision for biopsy, timely aggressive medical treatment, and follow-up of the disease to minimise possible complications.

Clinical characteristics and predictors for recurrence in chronic nonbacterial osteomyelitis: a retrospective multicenter analysis

Background/aim

Chronic nonbacterial osteomyelitis (CNO) is a rare disease of unknown etiology and most commonly occurs during childhood or adolescence. The purpose of this study is to collect data on the clinical features, outcomes, and management of the disease and to identify the factors affecting recurrence.

Materials and methods

This is a retrospective multicenter cross-sectional study of pediatric patients diagnosed with CNO. A total of 87 patients with a diagnosis of CNO followed for at least 6 months in 8 pediatric rheumatology centers across the country between January 2010 and December 2021 were included in this study.

Results

The study included 87 patients (38 girls, 49 boys; median age: 12.5 years). The median follow-up time was 20 months (IQR: 8.5-40). The median time of diagnostic delay was 9.9 months (IQR: 3-24). Arthralgia and bone pain were the most common presenting symptoms. Multifocal involvement was detected in 86.2% of the cases and a recurrent course was reported in one-third of those included in the study. The most commonly involved bones were the femur and tibia. Vertebrae and clavicles were affected in 19.5% and 20.6% of cases, respectively. The erythrocyte sedimentation rate (ESR) values of 60.9% of the patients were above 20 mm/h and the C-reactive protein values of 44.8% were above 5 mg/L. The remission rate was 13.3% in patients using nonsteroidal antiinflammatory drugs and 75.0% in those using biological drugs. Vertebral and mandibular involvement and high ESR values at the time of diagnosis were associated with recurrence.

Conclusion

In this multicenter study, CNO with vertebral and mandibular involvement and high ESR at diagnosis were associated with recurrence.

Retrospective Review of 80 Patients with Chronic Recurrent Multifocal Osteomyelitis Evaluated by Pediatric Orthopaedic Surgeons

Background: Chronic Recurrent Multifocal Osteomyelitis (CRMO) is a rare aseptic autoinflammatory disease with a wide and vague clinical presentation that often mimics infection, malignancy, or benign conditions, leading to a delayed diagnosis. We aimed to evaluate the clinical characteristics, differential diagnoses from evaluating pediatric orthopaedic surgeons, and compared the number of patients that could have avoided a biopsy in 80 patients with CRMO. Methods: Children diagnosed with CRMO at a single tertiary pediatric hospital in the United States between 2012 and 2022 who were evaluated by a pediatric orthopaedic surgeon were retrospectively reviewed. The differential diagnoses from the surgeons were recorded from their initial presentation. The Jansson criteria and Bristol Criteria were retrospectively applied to evaluate patients who could have been spared a biopsy. Results: 80 children (65% female) with CRMO were identified. The mean age at diagnosis was 10.28 ± 3.52 years, follow-up of 37.13 ± 27.67 months, and delay in diagnosis of 6.21 ± 9.75 months. Common presenting symptoms were antalgic gait (45%), local inflammation (30%), and fever/fatigue (26.25%). 58% presented clinically with unifocal symptoms, but 81% had multifocal disease on imaging. Radiographs were unremarkable in 35%, had periosteal reaction/sclerosis (23%), or a lytic lesion (22%). On MRI, 72% of patients had marrow edema, periosteal reaction (23%), and/or osteitis (19%). 69% of patients received a whole-body MRI, and 75% received a bone biopsy. The femur, tibia, pelvis, and spine were involved in >30% of patients. The most common initial differential diagnoses were related to infection (34%) and neoplasm (21%). The Jansson criteria was found to be more sensitive than the Bristol criteria for diagnosing CRMO (OR 3.94, P < 0.001) and identified 80% that could have been spared biopsy. Conclusions: This cohort of 80 patients with CRMO in the U.S. displayed an ambiguous presentation. Whole-body MRI was useful for identifying multifocal lesions. In conjunction with clinical reasoning, the Jansson criteria may be useful in the diagnosis of CRMO and perhaps avoid an unnecessary bone biopsy. Levels of Evidence: Level IV Key Concepts•Chronic Recurrent Multifocal Osteomyelitis is a rare condition in children with a delay in definitive diagnosis of approximately 6 months after initial presentation.•Chronic Recurrent Multifocal Osteomyelitis often has unremarkable radiographs and MRI findings similar to a neoplasm or infectious osteomyelitis.•The most common lesions were found in the femur, tibia, pelvis, and spine.•Pediatric orthopaedic surgeons evaluating these patients placed neoplasm/malignancy and infection on their differential most frequently.•The Jansson criteria may be used in some patients to possibly prevent unnecessary bone biopsies.