Dealing with Chronic Non-Bacterial Osteomyelitis: a practical approach

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.

Magnetic resonance imaging of the musculoskeletal system in the diagnosis of rheumatic diseases in the pediatric population

Magnetic resonance imaging (MRI) of the musculoskeletal system is an examination increasingly performed for suspected juvenile idiopathic arthritis, chronic nonbacterial osteomyelitis and juvenile idiopathic inflammatory myopathies, as well as other rheumatic diseases of developmental age. T1-, T2- and PD-weighted with or without fat suppression or short tau inversion recovery/turbo inversion recovery magnitude (STIR/TIRM) sequences and post-contrast sequences are evaluated to diagnose pathological changes in the synovial membrane, subchondral bone marrow and surrounding soft tissues. Magnetic resonance imaging allows detection of synovitis, tenosynovitis, bursitis, and enthesitis as well as bone marrow edema and soft tissue edema. Several pediatric-specific MRI scoring systems have been developed and validated to standardize and facilitate the assessment of the extent of the inflammatory process and disease activity in MRI. Early detection of inflammatory changes allows the inclusion of comprehensive pharmacotherapy giving the possibility of permanent remission and objective measurement of the effectiveness of treatment.

Pictorial review: challenges in distinguishing bilateral metaphyseal marrow abnormalities on magnetic resonance imaging

The paediatric metaphysis is afflicted by a wide range of pathological processes as it is the most metabolically active and well-vascularised part of the developing skeleton. This review focuses on metaphyseal marrow signal change detected with magnetic resonance imaging, which is most often occult on radiographs. When bilateral, these imaging appearances frequently present a diagnostic quandary. This review assists the radiologist to confidently dismiss physiological signal change and confidently work through the differential diagnosis. This is achieved by illustrating a practical method of classifying signal change into four categories: physiological red marrow, red marrow reconversion, marrow infiltration, and oedema-like marrow signal intensity. In doing so, various pathological entities are reviewed along with imaging pearls and next-step investigations.

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.

Reconstructive surgery with an autologous bone graft in a dog with presumptive chronic non-bacterial osteomyelitis

A 15-year-old Cocker Spaniel was referred to for the evaluation of left forelimb lameness. Radiographic and computed tomography examinations revealed osteolysis of the proximal left third, fourth and fifth metacarpal bones and pathological fractures of the proximal left fourth metacarpal bone. Histopathological examination via bone biopsy did not provide a definitive diagnosis, and the owner elected limb-sparing surgery. The fourth metacarpal bone and digits were amputated. Subsequently, autologous bone grafts were performed on the lytic area of the third and fifth metacarpal bones. The dog showed improvement in gait 7 weeks after reconstructive surgery. Chronic non-bacterial osteomyelitis (CNO) was diagnosed by exclusion. To the best of our knowledge, CNO has not been previously reported in dogs.

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.

Chronic Non-bacterial Osteomyelitis (CNO) In Childhood: A Review

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disorder mostly affecting children and adolescents. Although it is considered a rare disease, CNO is likely to be the single most common autoinflammatory bone disease in childhood, underdiagnosed and underreported due to a lack of awareness of the condition in both medics and patients and the absence of validated diagnostic criteria. The exact underlying pathogenesis of CNO remains unknown, making targeted treatment difficult. This issue is exacerbated by the lack of any randomised control trials, meaning that treatment strategies are based solely on retrospective reviews and case series. This review summarises the current concepts in pathophysiology, the clinical features that help differentiate important differential diagnoses, and an approach to investigating and managing children with CNO. Ultimately, the timely and thorough investigation of children and young people with CNO is vitally important to exclude important mimics and initiate appropriate management that can prevent the complications of persistent inflammatory bone disease.

Machine Learning Algorithm: Texture Analysis in CNO and Application in Distinguishing CNO and Bone Marrow Growth-Related Changes on Whole-Body MRI

OBJECTIVE

The purpose of this study is to analyze the texture characteristics of chronic non-bacterial osteomyelitis (CNO) bone lesions, identified as areas of altered signal intensity on short tau inversion recovery (STIR) sequences, and to distinguish them from bone marrow growth-related changes through Machine Learning (ML) and Deep Learning (DL) analysis.

MATERIALS AND METHODS

We included a group of 66 patients with confirmed diagnosis of CNO and a group of 28 patients with suspected extra-skeletal systemic disease. All examinations were performed on a 1.5 T MRI scanner. Using the opensource 3D Slicer software version 4.10.2, the ROIs on CNO lesions and on the red bone marrow were sampled. Texture analysis (TA) was carried out using Pyradiomics. We applied an optimization search grid algorithm on nine classic ML classifiers and a Deep Learning (DL) Neural Network (NN). The model's performance was evaluated using Accuracy (ACC), AUC-ROC curves, F1-score, Positive Predictive Value (PPV), Mean Absolute Error (MAE) and Root-Mean-Square Error (RMSE). Furthermore, we used Shapley additive explanations to gain insight into the behavior of the prediction model.

RESULTS

Most predictive characteristics were selected by Boruta algorithm for each combination of ROI sequences for the characterization and classification of the two types of signal hyperintensity. The overall best classification result was obtained by the NN with ACC = 0.91, AUC = 0.93 with 95% CI 0.91-0.94, F1-score = 0.94 and PPV = 93.8%. Between classic ML methods, ensemble learners showed high model performance; specifically, the best-performing classifier was the Stack (ST) with ACC = 0.85, AUC = 0.81 with 95% CI 0.8-0.84, F1-score = 0.9, PPV = 90%.

CONCLUSIONS

Our results show the potential of ML methods in discerning edema-like lesions, in particular by distinguishing CNO lesions from hematopoietic bone marrow changes in a pediatric population. The Neural Network showed the overall best results, while a Stacking classifier, based on Gradient Boosting and Random Forest as principal estimators and Logistic Regressor as final estimator, achieved the best results between the other ML methods.

Pediatric Gnathic Bony and Mesenchymal Tumors

Evaluation of bone pathology within the head and neck region, particularly the gnathic bonesis is complex, demonstrating unique pathologic processes. In part, this variation is due to odontogenesis and the embryological cells that may be involved, which can contribute to disease development and histologic variability. As with any boney pathosis, the key is to have clinical correlation, particularly with radiographic imaging prior to establishing a definitive diagnosis. This review will cover those entities that have a predilection for the pediatric population, and while it is not all inclusive, it should serve as a foundation for the pathologist who is evaluating bony lesions involving the craniofacial skeleton.

An unusual presentation of chronic recurrent multifocal osteomyelitis involving bones of the skull

Chronic recurrent multifocal osteomyelitis is a rare, multisystemic inflammatory disease that affects children and adolescents. We present the case of an African-American adolescent male who presented with recurrent swelling of the temporal region with skull involvement on head imaging, which is atypical for chronic recurrent multifocal osteomyelitis. He had clinical and laboratory improvement after initiation of indomethacin and pamidronate.

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.

Ankle and Foot: Focus on Inflammatory Disease

The ankle and foot have numerous bones and complex joints that can be affected by several types of inflammatory arthritis with different patterns and various radiologic signs, depending on the phase of the disease. Involvement of these joints is most frequently seen in peripheral spondyloarthritis and rheumatoid arthritis in adults and juvenile idiopathic arthritis in children. Although radiographs are a mainstay in the diagnostic process, ultrasonography and especially magnetic resonance imaging allow early diagnosis and are crucial diagnostic tools. Some diseases have typical features based on target populations (e.g., adults versus children, men versus women), but others may have overlapping imaging characteristics. We highlight key diagnostic features and describe appropriate investigations to guide clinicians toward the correct diagnosis and provide support during disease monitoring.

Chronic Nonbacterial Osteomyelitis of the Jaw in a 3-Year-Old Girl

Differential diagnosis of bacterial osteomyelitis (BOM) and chronic nonbacterial osteomyelitis (CNO) is challenging. Pediatric CNO can be diagnosed at around 10 years of age and when CNO cases involve only the jaw, it is difficult to make a diagnosis in a young child. A 3-year-old female developed CNO at the jaw alone. She presented with no fever, right jaw pain, mild trismus, and a preauricular facial swelling around the right mandible. Computed tomography (CT) revealed a hyperostotic right mandible, with osteolytic and sclerotic changes associated with periosteal reaction. At first, we suspected BOM and antibiotics were administered. Subsequently, CNO was diagnosed, and the patient received flurbiprofen (a nonsteroidal anti-inflammatory drug (NSAIDs)). Lack of a sufficient response led to successful treatment with a combination of oral alendronate and flurbiprofen. Physicians should be aware of CNO, a rare autoinflammatory noninfectious bone disease of unknown etiology, even in young children, although the disease mostly affects older children and adolescents.

Bell's palsy with facial bone involvement: A rare presentation of chronic nonbacterial osteomyelitis with literature review

Chronic nonbacterial osteomyelitis (CNO) is a chronic, sterile, inflammatory disease. It primarily presents with nonspecific bone pain and swelling but ultimately can cause bone destruction and deformities, if left untreated. The involvement of the cranial bones (apart from the mandible) is rare in CNO. In this report, we present a rare case of CNO affecting facial and cranial bones presenting as facial palsy with a review of the literature about similar affection. A 10-year-old, previously healthy female was initially evaluated for swelling of the left side of her face with slight tenderness on palpation, but no fever. Her complete blood count was unremarkable, her inflammatory markers were elevated (C-reactive protein 7.5 mg/dl and erythrocyte sedimentation rate 104 mm/h), and CT of facial and skull bones and MRI of brain showed a destructive osseous process involving the left maxillary, zygomatic, sphenoid bones and the clivus. Bone biopsy of the left maxilla showed fibrous dysplasia with abscess formation, most consistent with an infectious aetiology (acute osteomyelitis). She was started on oral clindamycin for a 3-month course. The facial swelling improved after starting clindamycin, but on her sixth week of treatment, she developed right-sided Bell's palsy. An MRI of the brain showed hyperenhancement of the right seventh cranial nerve. A month later, she was evaluated for right wrist and knee swelling, pain, and limitation of movement. Skeletal survey and MRI showed multifocal lesions with mixed sclerosis and lucency. Her inflammatory markers continued to be elevated. Another bone biopsy of the right radius showed similar findings of destruction with no evidence of malignancy. She was ultimately diagnosed with CNO. She was started on nonsteroidal anti-inflammatory drugs with gastric protection and regular follow-up. Over more than a year of follow-up, the patient's inflammatory markers remain normal, and joint swelling/limitation has remained in remission. We found five additional cases in the literature that presented with a similar presentation. To our knowledge, our patient is the first reported case in the USA involving the cranial/facial bones apart from the mandible presenting with facial palsy. The affection of the facial bones (apart from the mandible) in CNO is very rare, but the awareness of such a presentation by the clinician is an important aspect of reaching the diagnosis.

Efficacy and Safety of NSAIDs in Infants: A Comprehensive Review of the Literature of the Past 20 Years

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in infants, children, and adolescents worldwide; however, despite sufficient evidence of the beneficial effects of NSAIDs in children and adolescents, there is a lack of comprehensive data in infants. The present review summarizes the current knowledge on the safety and efficacy of various NSAIDs used in infants for which data are available, and includes ibuprofen, dexibuprofen, ketoprofen, flurbiprofen, naproxen, diclofenac, ketorolac, indomethacin, niflumic acid, meloxicam, celecoxib, parecoxib, rofecoxib, acetylsalicylic acid, and nimesulide. The efficacy of NSAIDs has been documented for a variety of conditions, such as fever and pain. NSAIDs are also the main pillars of anti-inflammatory treatment, such as in pediatric inflammatory rheumatic diseases. Limited data are available on the safety of most NSAIDs in infants. Adverse drug reactions may be renal, gastrointestinal, hematological, or immunologic. Since NSAIDs are among the most frequently used drugs in the pediatric population, safety and efficacy studies can be performed as part of normal clinical routine, even in young infants. Available data sources, such as (electronic) medical records, should be used for safety and efficacy analyses. On a larger scale, existing data sources, e.g. adverse drug reaction programs/networks, spontaneous national reporting systems, and electronic medical records should be assessed with child-specific methods in order to detect safety signals pertinent to certain pediatric age groups or disease entities. To improve the safety of NSAIDs in infants, treatment needs to be initiated with the lowest age-appropriate or weight-based dose. Duration of treatment and amount of drug used should be regularly evaluated and maximum dose limits and other recommendations by the manufacturer or expert committees should be followed. Treatment for non-chronic conditions such as fever and acute (postoperative) pain should be kept as short as possible. Patients with chronic conditions should be regularly monitored for possible adverse effects of NSAIDs.

Standardized reporting and quantification of whole-body MRI findings in children with chronic non-bacterial osteomyelitis treated with pamidronate

OBJECTIVES

The objectives were to assess changes in radiological disease activity in children with chronic non-bacterial osteomyelitis (CNO) receiving pamidronate therapy and to test a modified radiological index for non-bacterial osteitis (mRINBO) in CNO. mRINBO was used for standardized reporting and quantification of whole-body MRI (WBMRI) findings resulting in an individual summary patient score.

METHODS

WBMRI was retrospectively assessed in 18 children with CNO at baseline and after receiving pamidronate therapy for one year. Parameters of interest were: number and anatomic site of radiologically active bone lesions (RAL), size of RAL, extramedullary affection, spinal involvement and changes in mRINBO, which includes both the number and maximal size of RAL (RALmax) in addition to extramedullary and chronic changes.

RESULTS

At the time of diagnosis, the mean age of the children was 9.8 (sd, 8.7-10.9) years and 11/18 were females. The number of RALs per patient decreased from median [interquartile range] 4.5 [3-8] to 3 [2-5] RALs per patient (p = 0.02) and extramedullary inflammatory changes regressed. Sixty-one percent of all RALs occurring at baseline resolved and three children became without active inflammatory lesions by WBMRI. The median size of RALs did not change when taking new lesions occurring in 7/18 children into account, but RALmax decreased significantly from 39 [29-45] mm at baseline to 28 [20-40] mm (p < 0.01) at year-one with a concomitant decrease of mRINBO from a median of 5 [4-7] to 4 [3-5] (p = 0.05).

CONCLUSIONS

Pamidronate therapy resulted in a decrease of mRINBO from baseline to year one. mRINBO may be a potential scoring method to quantify changes in radiological disease activity in children with CNO. However, further studies are needed to test feasibility and validity of mRINBO.

Chronic nonbacterial osteomyelitis: the role of whole-body MRI

Background

Chronic nonbacterial osteomyelitis (CNO), also known as chronic recurrent multifocal osteomyelitis, is a noninfectious autoinflammatory disorder that occurs primarily in children and adolescents and is characterized by episodic musculoskeletal pain with a protracted course.

Main body

Traditionally, the diagnosis of CNO is made by exclusion and commonly requires bone biopsy to rule out infection and malignancy. However, bone biopsy may be avoided when imaging and clinical characteristic features are present, such as multifocal bone lesions at typical sites, no constitutional symptoms and no signs of infection in laboratory test results. Whole-body magnetic resonance imaging (WB-MRI) can assess signs of acute and chronic inflammation and enables the detection of CNO typical patterns of lesion location and distribution, thereby helping to exclude differential diagnosis. The goal of the present study paper is to review the main clinical and imaging aspects of the disease with emphasis on the role of WB-MRI in the diagnosis, assessment of disease burden and follow-up monitoring.

Conclusion

Radiologists need to be familiar with the imaging features to suggest the diagnosis as the early therapy may help to avoid irreversible secondary damage of skeletal system.

Chronic recurrent multifocal osteomyelitis, a rare disease. Case report

Introduction: Chronic recurrent multifocal osteomyelitis (CRMO) is a rare inflammatory bone disease usually observed in children and adolescents. It is caused by an imbalance between proinflammatory and anti-inflammatory factors. To establish its diagnosis, it is necessary to integrate clinical and laboratory elements that are typically aimed at ruling out other conditions, constituting a diagnosis of exclusion. Treatment is based on non-steroidal anti-inflammatory drugs and other drugs in specific cases. Case presentation: A 16-year-old female patient with a 1-year history of joint pain, especially in the knees, accompanied by signs of local inflammation was admitted to the emergency department of a quaternary care hospital due to a fever >38.5°, odynophagia, asthenia, and adynamia over the last two days. The patient underwent multiple extension studies, including laboratory, imaging and histopathological tests, which ruled out various etiologic causes. She received empirical antibiotic treatment without remission of symptoms, so a diagnosis of CRMO was finally established and outpatient treatment with non-steroidal anti-inflammatory drugs and corticosteroids was indicated, obtaining a favorable response. Conclusions: CRMO should be considered in children and adolescents with bone pain and a poorly defined clinical history with non-specific laboratory, imaging and histopathological findings. To date, little is known about CRMO, so it is necessary to carry out research and expand the knowledge related to this disease.

Nanotechnology in the Diagnosis and Treatment of Osteomyelitis

Infection remains one of the largest threats to global health. Among those infections that are especially troublesome, osteomyelitis, or inflammation of the bone, typically due to infection, is a particularly difficult condition to diagnose and treat. This difficulty stems not only from the biological complexities of opportunistic infections designed to avoid the onslaught of both the host immune system as well as exogenous antibiotics, but also from changes in the host vasculature and the heterogeneity of infectious presentations. While several groups have attempted to classify and stage osteomyelitis, controversy remains, often delaying diagnosis and treatment. Despite a host of preclinical treatment advances being incubated in academic and company research and development labs worldwide, clinical treatment strategies remain relatively stagnant, including surgical debridement and lengthy courses of intravenous antibiotics, both of which may compromise the overall health of the bone and the patient. This manuscript reviews the current methods for diagnosing and treating osteomyelitis and then contemplates the role that nanotechnology might play in the advancement of osteomyelitis treatment.

Chronic Recurrent Multifocal Osteomyelitis: A Review of the Noninfectious Inflammatory Bone Disease and Lessons for More Timely Diagnosis

Chronic recurrent multifocal osteomyelitis (CRMO) is an idiopathic autoinflammatory disease of the bone that typically occurs in children and adolescents. CRMO is characterized by recurrent periods of exacerbation and remission of symptomatic, osteolytic/sclerotic sterile bone lesions and is often a diagnosis of exclusion. Treatment consists of multimodal anti-inflammatory medication management by rheumatology and rarely involves surgery. This review summarizes the clinical presentation, pathophysiology, diagnosis, and management of this disease and highlights the role of the orthopedic surgeon. With increased familiarity with CRMO, clinicians will be able to diagnose and treat the condition in a more timely manner. [Orthopedics. 202x;4x(x):xx-xx.].

Nano Sized Hydroxyapatite-Polylactic Acid-Vancomycin in Alleviation of Chronic Osteomyelitis

Background

Objective

Methods

Results

Conclusion

Chronic Non-infectious Osteomyelitis Mimicking Scurvy as the Presenting Sign of Crohn's Disease: Case Report

Chronic non-infectious osteomyelitis (CNO) is a rare, inflammatory process associated with pediatric inflammatory bowel disease (IBD). Signs and symptoms of CNO parallel scurvy, a nutritional deficiency that can affect children with autism spectrum disorder (ASD). This is the first report of a child initially thought to have scurvy, then subsequently diagnosed with CNO as the presenting manifestation of Crohn's disease. This case enhances the literature elucidating extra-intestinal manifestations of IBD and pediatric nutritional deficiencies.

Ultrasound evaluation of inflammation in patients with chronic recurrent multifocal osteomyelitis involving the mandible: report of three cases

Chronic recurrent multifocal osteomyelitis (CRMO) is aseptic and can be diagnosed by excluding other diseases, such as bacterial osteomyelitis, scurvy, metabolic disorders, and malignant diseases; therefore, bone biopsy is usually performed to confirm the diagnosis. To prevent misdiagnosis, the appropriate timing and location for biopsy should be determined from an active phase of inflammation. We presented 3 cases of CRMO involving the mandible: Case 1: A 2-year-old girl diagnosed with CRMO in the chronic phase. A sonogram showed a slightly low echoic area adjacent to the bone cortex. Pathological examination revealed a slight accumulation of leukocytes and plasma cells, as well as predominant fibrous stroma. Case 2: A 9-year-old girl diagnosed with CRMO with massive new osteoid formation. A sonogram showed a massive inhomogeneous low echoic area adjacent to the bone cortex. Pathological examination revealed massive osteoid formation and scattered inflammatory cells infiltration. Case 3: A 3-year-old girl diagnosed with CRMO in the active phase. A sonogram showed a massive hypoechoic area adjacent to the bone cortex and hyperechogenicity associated with a muscular and subcutaneous edema. Pathological examination revealed massive bone destruction and neutrophils infiltration within damaged osteoid. Ultrasound was able to visualize the degree of inflammation in the mandible corresponding to that of the surrounding soft tissue in all 3 cases. Therefore, ultrasound would be useful in determining the appropriate timing and location for bone biopsy.

Acute Arthritis in Children: How to Discern between Septic and Non-Septic Arthritis?

The term septic arthritis refers to an infection of the synovial space. This is an infrequent condition in healthy children, but it should be considered a medical emergency potentially leading to irreversible articular damage. Therefore, prompt diagnosis and antimicrobial treatment play a crucial role in improving the prognosis. Although septic arthritis is the most common cause of acute arthritis, many other diseases may mimic a similar clinical picture, constituting a diagnostic challenge for the clinician who first approaches the patient. Herein we analyze the main features of septic arthritis, offering an overview of the main conditions involved in the differential diagnosis and suggesting a diagnostic workup plan.

Role of Diagnostic Imaging in Chronic Recurrent Multifocal Osteomyelitis (CRMO) in Children: An Observational Study

The aim of this single-center observational study was to analyze the applicability of various imaging studies to the diagnosis and further evaluation of patients with chronic recurrent multifocal osteomyelitis (CRMO). The analysis included the data of 10 patients with CRMO treated between 2016 and 2021. The mean ages of the patients at the first manifestation of CRMO and ultimate diagnosis were 10 years and 7 months and 11 years and 10 months, respectively. Conventional radiography demonstrated focal loss of bone density in only 30% of the patients. Computed tomography showed disseminated foci with non-homogeneous osteolytic/osteosclerotic structure, with a massive loss of cortical layer and strong periosteal reaction. On magnetic resonance imaging (MRI), most patients presented with multifocal hypodense areas on T1-weighted images, with the enhancement of signal on T-weighted and STIR sequences. The duration of follow-up varied between 3 months and 3 years. In 40% of the patients, both clinical symptoms and the abnormalities seen on MRI resolved completely, whereas another 50% showed partial regression of clinical and radiological manifestations. MRI findings, co-existing with characteristic clinical manifestations, play a pivotal role in establishing the ultimate diagnosis of CRMO. MRI can also be used to monitor the outcomes of treatment in CRMO patients.

[Imaging features of osteomyelitis of the jaws with different diagnostic methods. A review]

Osteomyelitis of the jaws (OM) is an infectious pathology involving the bone marrow. It is due to various etiologies, the main one being odontogenic. The diagnosis of OM is a challenge for dentists, who must rely on clinical and imaging examinations. Panoramic radiography is the most frequently used imaging test, but it has some limitations that have improved with the incorporation of new imaging methods such as computed tomography, cone beam computed tomography, magnetic resonance imaging, and bone scintigraphy with radionuclides. The purpose of this review was to describe the imaging characteristics of OM of the jaws according to the radiological diagnostic methods available in the literature in order to provide radiologisst with greater knowledge and improve reporting in daily practice.

Chronic Nonbacterial Osteomyelitis in Children

Chronic nonbacterial osteomyelitis (CNO) is an auto-inflammatory bone disorder with a wide spectrum of clinical manifestations, from unifocal to multifocal lesions. When it manifests with multifocal lesions, it is also referred to as chronic recurrent multifocal osteomyelitis (CRMO). CNO/CRMO can affect all age groups, with the pediatric population being the most common. Patients may present with systemic inflammation, but there is no pathognomonic laboratory finding. Magnetic resonance imaging (MRI) is the gold standard radiological tool for diagnosis. In the absence of validated diagnostic criteria, CNO/CRMO remains an exclusion diagnosis. Bone biopsy does not show a specific disease pattern, but it may be necessary in unifocal or atypical cases to differentiate it from malignancy or infection. First-line treatments are non-steroidal anti-inflammatory drugs (NSAIDs), while bisphosphonates or TNF-α blockers can be used in refractory cases. The disease course is unpredictable, and uncontrolled lesions can complicate with bone fractures and deformations, underlying the importance of long-term follow-up in these patients.

Patient-reported effectiveness and safety of Pamidronate in NSAIDs-refractory chronic recurrent multifocal osteomyelitis in children

To evaluate patient-reported effectiveness, safety and social influence of Pamidronate in the therapy of NSAIDs-refractory Chronic Recurrent Multifocal Osteomyelitis in children. Authors reviewed self-created questionnaires, which asked patients for symptoms alleviation, adverse drug reactions frequency and degree of severity and daily activities self-reliance. Only surveys with complete answers, which were returned to authors by an e-mail from juvenile patients treated for NSAIDs-refractory Chronic Recurrent Multifocal Osteomyelitis at the University Children’s Hospital of Cracow were analyzed. Between 2010 and 2019, 61 children were diagnosed with NSAIDs-refractory Chronic Recurrent Multifocal Osteomyelitis at our department. Out of 61 requests sent, 42 complete replies (33 females, 9 males) were gathered and analyzed. All patients included in this research were administered with at least one set of Pamidronate intravenously in the dose of 1 mg/kg/day for 3 consecutive days. Our analysis shows remarkable in terms of patient’s impressions decrease of pain intensity after 2.5 series of Pamidronate on average, and total pain resolution after 5.9 series on average. Overall number of adverse drug reaction events reported by responders was 105. One patient developed drug-dependent renal insufficiency in the course of therapy. Outcome assessment indicates that nearly 50% of the studied population was more eager to participate in social life just after the first infusion of the drug. 95% of the surveyed unanimously agreed to recommend Pamidronate therapy to cure NSAIDs-refractory CRMO. 39 out of 42 (93%) patients considered Pamidronate effective at the end of the treatment. Onset of Pamidronate’s action is gradual and differs in terms of symptoms alleviation between sexes. The therapy can induce considerable number of adverse drug reactions (2.5 per patient). Only 3 out of 42 (7%) patients were free from any ADRs. To demonstrate the impact of the use of Pamidronate on daily activities more precisely, further research with quantification of the quality of life is warranted.

Genomic Expression Profiling and Bioinformatics Analysis of Chronic Recurrent Multifocal Osteomyelitis

Objective

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder. Its most severe form is referred to as chronic recurrent multifocal osteomyelitis (CRMO). Currently, the exact molecular pathophysiology of CNO/CRMO remains unknown. No uniform diagnostic standard and treatment protocol were available for this disease. The aim of this study was to identify the differentially expressed genes (DEGs) in CRMO tissues compared to normal control tissues to investigate the mechanisms of CRMO.

Materials

Microarray data from the GSE133378 (12 CRMO and 148 matched normal tissue samples) data sets were downloaded from the Gene Expression Omnibus (GEO) database. DEGs were identified using the limma package in the R software. Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and protein-protein interaction (PPI) network analysis were performed to further investigate the function of the identified DEGs.

Results

This study identified a total of 1299 differentially expressed mRNAs, including1177 upregulated genes and 122 downregulated genes, between CRMO and matched normal tissue samples. GO analyses showed that DEGs were enriched in immune-related terms. KEGG pathway enrichment analyses showed that the DEGs were mainly related to oxidative phosphorylation, ribosome, and Parkinson disease. Eight modules were extracted from the gene expression network, including one module constituted with immune-related genes and one module constituted with ribosomal-related genes.

Conclusion

Oxidative phosphorylation, ribosome, and Parkinson disease pathways were significantly associated with CRMO. The immune-related genes including IRF5, OAS3, and HLA-A, as well as numerous ribosomal-related genes, might be implicated in the pathogenesis of CRMO. The identification of these genes may contribute to the development of early diagnostic tools, prognostic markers, or therapeutic targets in CRMO.

A case of bone destruction caused by chronic non-bacterial osteomyelitis (CNO) successfully repaired with a tumour necrosis factor-α (TNF-α) inhibitor, adalimumab

Chronic Non-bacterial Osteomyelitis (CNO) is an autoinflammatory bone disorder that causes non-bacterial and non-neoplastic osteomyelitis. CNO appeared to the long bone, clavicle, pelvis, and spine on children commonly. This time, we report a case with osteomyelitis of the mandible for the adult-onset. A 25-year-old woman presented pustulosis palmaris/pustular psoriasis after the extraction of the lower right tooth 1 year before hospitalisation. She felt pain and swelling of the right jaw and an antibiotic, NSAIDs, and glucocorticoids were ineffective. The cortical osteotomy of right mandibular bone was carried out 2 months before hospitalisation, but the symptom was not improved and she was admitted to our hospital. For pustular psoriasis with CNO, we treated her with adalimumab and the pain and swelling in her right jaw disappeared immediately. One and two years after the treatment, osteolytic and sclerotic bone lesion and osteomyelitis were improved in both Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). An anti-TNF-α antibody may be an effective therapy for CNO resistant to conventional treatment.

Chronic Nonbacterial Osteomyelitis

A 9-year-old active girl presented to physical therapy via direct access with intermittent severe pain deep in the distal third of her left thigh that had a 2-year history. Twenty months prior, her pediatrician ordered radiographs that were noncontributory and diagnosed her with "growing pains." During examination, an osseous nontender enlargement of the femur was found proximal to the patella, and the patient was referred to her pediatrician for imaging. Radiographs demonstrated an expansile bone lesion with a mixed matrix and an open surgical biopsy determined the mass to be consistent with nonbacterial osteomyelitis. J Orthop Sports Phys Ther 2020;50(10):585. doi:10.2519/jospt.2020.9221.

[Chronic nonbacterial osteomyelitis : Imaging and differential diagnoses]

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disease in childhood and adolescence with a preference for the female gender. It is manifested with multiple osseous lesions, with a predilection for the metaphyseal end zones of the long bones of the lower extremities. These bone lesions usually occur multifocally, can recur and develop a different appearance depending on the bone structure affected. Patients present with a longer disease history, changing clinical symptoms and unspecific paraclinical signs. Magnetic resonance imaging (MRI) is the imaging of choice and particularly as a whole body examination can speed up the diagnosis and is an important component of follow-up controls. Differential diagnoses include numerous inflammatory, benign and malignant bone diseases. Therefore, it is essential to know the diagnosis of CNO and to take it into consideration in cases of an unclear inflammatory bone process in young patients.

Oral administration of alendronate and vitamin D3 for the treatment of chronic non-bacterial osteomyelitis of the jaw

Chronic non-bacterial osteomyelitis (CNO) is a rare and difficult-to-diagnose disease, especially when limited to the jaws. We report the case of a 5-year-old girl with spontaneous jaw pain and a large pre-auricular facial swelling overlying the angle of the mandible that was non-responsive to previous antibiotic and non-steroidal anti-inflammatory treatment. The diagnosis was confirmed as CNO following evaluation and workup by a multidisciplinary team. The patient exhibited a favourable response to oral alendronate sodium plus vitamin D3 combination treatment. We believe that alendronate sodium is an effective second-line drug for CNO.

High prevalence of rare FBLIM1 gene variants in an Italian cohort of patients with Chronic Non-bacterial Osteomyelitis (CNO)

BACKGROUND

FBLIM1 gene has been recently demonstrated to be involved in the pathogenesis of bone sterile inflammation. The aim of the study is to evaluate the prevalence of FBLIM1 gene variants in a cohort of 80 Italian patients with Chronic Non-bacterial Osteomyelitis (CNO).

METHODS

The coding regions of FBLIM1 gene were sequenced in a cohort of 80 patients with CNO using DNA extracted from blood lymphocytes, and PCR products were sequenced. Only rare (global MAF < 2%), coding variants detected were considered. Clinical evaluation of patients with rare variants and those without was performed. Fisher's exact test was used to compare categorical and ordinal data, and Student's t-test was used to analyze continuous data.

RESULTS

Eighteen out of 80 patients (~ 22%) presented at least one rare coding variant in FBLIM1. Eight patients presented a variant never associated before with CNO. All patients presented classical features of CNO and no statistical difference between patients with presence of FBLMI1 variants and those without were found in terms of clinical manifestation, treatment, and outcome.

CONCLUSION

Considering the high frequency of rare variants in our CNO cohort, our data seem to confirm a possible role of FBLIM1 in the pathogenesis of CNO suggesting that CNO is a disorder of chronic inflammation and imbalanced bone remodeling.

Favorable outcome of extended curettage for the treatment of unifocal chronic sclerosing osteomyelitis of clavicle: a case series

BACKGROUND

Chronic sclerosing osteomyelitis (CSO) of the clavicle, especially its unifocal subset, is scarcely reported, and little is known about its characteristic features and treatment. We aim to describe the characteristic features and outcome of treatment in a series of patients with unifocal CSO of the clavicle.

MATERIALS AND METHODS

In a retrospective study, we identified 6 patients with a diagnosis of unifocal CSO of the clavicle. All patients underwent a core needle biopsy, and histologic examination confirmed the diagnosis. Laboratory investigations included the white blood cell count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, and bacteriologic culture. We used plain radiographs, computed tomography scanning, and magnetic resonance imaging for the radiologic evaluation.

RESULTS

The median age of the patients was 16.5 years (range, 10-29 years). The ESR and CRP level were elevated in 5 cases. The bacterial culture results were negative in all cases. Sclerosis was the main radiologic symptom. Other radiologic features such as bone expansion, cystic change, periosteal reaction, cortex destruction, and soft-tissue edema could accompany sclerosis. Anti-inflammatory medications temporarily and slightly reduced the symptoms. Four patients underwent extended curettage, in whom the clinical, radiologic, and laboratory symptoms considerably subsided. In the 2 patients who did not agree to undergo surgical intervention, the clinical and radiologic symptoms fluctuated at the follow-up visits.

CONCLUSION

Unifocal CSO of the clavicle is associated with negative bacterial culture results, but the ESR and CRP level are frequently elevated. The symptoms fluctuate if not adequately treated. Extended curettage could be regarded as the treatment of choice.

Chronic recurrent multifocal osteomyelitis in pediatrics: A diagnostic challenge

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory disease that presents with aseptic bone inflammation and can be accompanied by multisystemic symptoms. We present the case of a 14-year-old male with a 2-week history of pain located at the tibial metaphysis and fever. X-ray revealed a lytic lesion in the tibial metaphysis. MRI revealed an intramedullary bone lesion with perilesional bone oedema. CT-guided biopsy discounted malignancy and microbiological cultures were negative. The patient's symptoms and fever worsened after the biopsy; therefore antibiotherapy was commenced for a suspected superinfection. A body MRI was performed given the persistence of the fever, which found a second active lesion in the spine that was diagnosed as CRMO and progressed well with anti-inflammatories. CRMO is an entity that is difficult to diagnose. Differential diagnosis is extensive with infectious diseases, tumours and other autoinflammatory diseases. Prompt diagnosis and appropriate treatment are crucial to prevent sequelae.

Response of Different Treatment Protocols to Treat Chronic Non-Bacterial Osteomyelitis (CNO) of the Mandible in Adult Patients: A Systematic Review

(1) Background: Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disease of finally unknown etiology, which can occur alone or related with syndromes (chronic recurrent multifocal osteomyelitis-CRMO; synovitis, acne, pustulosis, hyperostosis and osteitis syndrome-SAPHO). The involvement of the mandible is rather rare. (2) Methods: We carried out a systematic literature search on CNO with mandibular involvement, according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines, considering the different synonyms for CNO, with a special focus on therapy. (3) Results: Finally, only four studies could be included. A total of 36 patients were treated in these studies-therefore, at most, only tendencies could be identified. The therapy in the included works was inconsistent. Various therapies could alleviate the symptoms of the disease. A complete remission could only rarely be observed and is also to be viewed against the background of the fluctuating character of the disease. The success of one-off interventions is unlikely overall, and the need for long-term therapies seems to be indicated. Non-steroidal anti-inflammatory drugs (NSAIDs) were not part of any effective therapy. Surgical therapy should not be the first choice. (4) Conclusions: In summary, no evidence-based therapy recommendation can be given today. For the future, systematic clinical trials on therapy for CNO are desirable.

Chronic recurrent multifocal osteomyelitis: a case report

Chronic recurrent multifocal osteomyelitis is a rare autoinflammatory, immunologic disorder. It may involve recurrent inflammatory bone pain associated with aseptic osteomyelitis. If the diagnosis is delayed, it negatively influences quality of life by leading to persistent symptoms or joint damage. Herein, we report a 16-year-old male patient who presented with left hip and right knee pain lasting for the last two months and was diagnosed as having chronic recurrent multifocal osteomyelitis as a result of further evaluation. Improvement was achieved with prednisolone and methotrexate treatment that was initiated when no response to ibuprofen treatment could be obtained. Chronic recurrent multifocal osteomyelitis must be considered in the differential diagnosis in patients presenting with joint symptoms when clinical and radiologic bone lesions are found, no microorganism growth is observed, and no response to antibiotic treatment is obtained.

Periodic fever syndromes and the autoinflammatory diseases (AIDs)

Innate immune system represents the ancestral defense against infectious agents preserved along the evolution and species; it is phylogenetically older than the adaptive immune system, which exists only in the vertebrates. Cells with phagocytic activity such as neutrophils, macrophages, and natural killer (NK) cells play a key role in innate immunity. In 1999 Kastner et al. first introduced the term “autoinflammation” describing two diseases characterized by recurrent episodes of systemic inflammation without any identifiable infectious trigger: Familial Mediterranean Fever (FMF) and TNF Receptor Associated Periodic Syndrome (TRAPS). Autoinflammatory diseases (AIDs) are caused by self-directed inflammation due to an alteration of innate immunity leading to systemic inflammatory attacks typically in an on/off mode. In addition to inflammasomopathies, nuclear factor (NF)-κB-mediated disorders (also known as Rhelopathies) and type 1 interferonopathies are subjects of more recent studies.

This review aims to provide an overview of the field with the most recent updates (see “Most recent developments in..” paragraphs) and a description of the newly identified AIDs.

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Autoinflammatory diseases are caused by self-directed inflammation.

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Alteration of innate immunity leads to systemic inflammation attacks.

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The autoinflammatory field is exponentially expanding.

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The advances in AIDs have led to new insights into immune system understanding.

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Autoimmunity and autoinflammation features may be simultaneously present.

Clinical characteristics and treatment of clavicular osteomyelitis: a systematic review with pooled analysis of 294 reported cases

BACKGROUND

It is usually difficult to diagnose clavicular osteomyelitis (OM), and treatment is delayed because of its rarity. This study aimed to summarize clinical characteristics and treatment of this disease.

METHODS

We searched the PubMed and Embase databases to identify English studies that reported on clavicular OM from January 1980 through December 2016. Effective data were pooled for analysis.

RESULTS

In total, 111 studies comprising 294 cases (bacterial OM, 146; nonbacterial OM, 148) were included, with a sex ratio of 1.89:1 indicating female predilection. Overall, the median age at diagnosis was 16 years. The acute to chronic phase ratio was 0.30, with a median symptom duration of 4 months. The most frequently reported symptom was pain (192 cases), followed by swelling (151 cases) and fever (52 cases). Altogether, 86.94% cases of single-site involvement were reported, with the medial side being the most common site (69.95%). The erythrocyte sedimentation rate achieved the highest positive rate (74.44%) before treatment. The total positive rate of culture for bacterial OM was 81.82%, with Staphylococcus aureus being the most frequently detected pathogen (44.70%). The average cure rate was 83.52%, with no significant difference between surgical (89.70%) and nonsurgical (79.63%) cases (P = .079).

CONCLUSIONS

Clavicular OM, predominant in female patients and young people, usually occurred at a chronic stage. Pain was the most frequent symptom, with the medial side being the most involved site. The erythrocyte sedimentation rate may be a helpful indicator for diagnosis. Regardless of surgery or nonsurgery, most patients achieved a favorable prognosis.

Diagnostic and therapeutic difficulties in a patient with chronic recurrent multifocal osteomyelitis coexisting with ulcerative colitis

Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory bone disease, affecting mainly children. CNO includes a broad clinical spectrum of symptoms and signs, from mild, limited in time, unifocal osteitis to severe, chronic, active or recurrent, multifocal osteomyelitis. In 2014 diagnostic criteria for CNO were proposed, the Bristol Criteria for the Diagnosis of Chronic Non-bacterial Osteitis, taking into account the clinical picture – location and number of inflammatory foci, characteristic changes on radiological examination (X-ray) and magnetic resonance imaging (MRI), C-reactive protein (CRP) concentration, and changes in bone biopsy.

The paper presents the case of a four-year-old boy in whom the diagnosis of multifocal osteomyelitis coexisting with ulcerative colitis was established. Attention was paid to the long diagnostic process of the disease, requiring in the first place differentiation with proliferative diseases. The choice of drugs was also a significant problem in the patient described in view of both intolerance of individual preparations and their ineffectiveness.

Chronic Non-bacterial Osteomyelitis: A Review

Chronic non-bacterial osteomyelitis (CNO) is a rare auto-inflammatory bone disorder, with a prevalence of around one in a million patients. In the more severe form, it is referred to as chronic recurrent multifocal osteomyelitis (CRMO). We present the current knowledge on epidemiology, pathophysiology as well as diagnostic options and treatment regimens. CNO/CRMO most commonly affects children and lesions are often seen in the metaphyseal plates of the long bones, but cases have been described affecting all age groups as well as lesions in almost every bone. It is, therefore, a disease that clinicians can encounter in many different settings. Diagnosis is mainly a matter of exclusion from differential diagnoses such as bacterial osteomyelitis and cancer. Magnetic resonance imaging is the best radiological method for diagnosis coupled with a low-grade inflammation and a history of recurring episodes. Treatment is based on case reports and consists of alleviating symptoms with non-steroidal anti-inflammatory drugs since the disease is often self-limiting. Recently, more active treatments using either bisphosphonates or biological treatment are becoming more common, to prevent long term bone damage. In general, due to its rarity, much remains unclear regarding CNO/CRMO. We review the known literature on CNO/CRMO and propose areas of interest as well as possible ways to make current diagnostic criteria more detailed. We also find unifocal cases of the jaw to be a possible sub-type that may need its own set of criteria.

Response to Early-onset Pamidronate Treatment in Chronic Nonbacterial Osteomyelitis: A Retrospective Single-center Study

OBJECTIVES

Chronic nonbacterial osteomyelitis (CNO) is a sterile inflammatory bone disorder with an unpredictable disease course. The objective was to assess clinical and radiological disease activity in children with CNO including response to early-onset pamidronate treatment.

METHODS

A single-center retrospective study was conducted of children fulfilling the Bristol Criteria for CNO. At the time of diagnosis, whole-body magnetic resonance imaging (WB-MRI) or local MRI was performed to assess radiological disease activity. Children with multifocal or spinal bone inflammation and clinical disease activity not responding to nonsteroidal antiinflammatory drugs were categorized as having extended CNO. Clinical disease activity was assessed annually.

RESULTS

Fifty-one children were included. Median followup time was 4 years (interquartile range 3-7). Children categorized with extended CNO (n = 32) were treated in an early-onset 2-year pamidronate regimen. In extended CNO, WB-MRI was performed at time of diagnosis, and at years 1 and 2 in 88%, 84%, and 91% of cases, respectively. During the first year, the total number of radiologically active lesions and number of spinal lesions per patient declined (p = 0.01). Clinically inactive disease was recorded in 12/32 children (38%). However, 8/12 children (67%) experienced clinical relapse. In limited CNO (n = 19), 10/19 children (53%) presented with clinically inactive disease after 1 year and did not experience clinical relapse.

CONCLUSION

Pamidronate might contribute to improvement in clinical and radiological disease activity in extended CNO, especially after 1 year of treatment. However, children with continuously active disease after 2 years of pamidronate treatment were seen.