Imaging mimics of chronic recurrent multifocal osteomyelitis: avoiding pitfalls in a diagnosis of exclusion

Diagnostic Role of FDG PET/CT in Pediatric Patients With Chronic Recurrent Multifocal Osteomyelitis

PURPOSE

Chronic recurrent multifocal osteomyelitis (CRMO), or chronic nonbacterial osteomyelitis, is difficult to diagnose. The accurate diagnosis of CRMO relies on comprehensive imaging examinations because of its multifocal nature. In this regard, 18 F-FDG PET/CT has demonstrated significant utility in inflammatory diseases. This study tries to determine the value of FDG PET/CT in the evaluation of CRMO.

PATIENTS AND METHODS

We retrospectively collected imaging data from pediatric CRMO patients who underwent FDG PET/CT scans. Lesions exhibiting abnormal metabolism with/without structural abnormalities on FDG PET/CT were identified as CRMO lesions, and their location and SUV max were recorded.

RESULTS

A total of 21 pediatric patients with CRMO were included in this study. The median age at diagnosis was 9.4 years. Total 131 foci of abnormal activity were identified using FDG PET/CT imaging. The distribution pattern showed a higher prevalence of lower limbs and pelvis involvement. Among all identified lesions, abnormalities were detected on both PET and CT images of 93 lesions, whereas exclusively positive findings on 18 F-FDG PET alone were observed for 38 of them.

CONCLUSIONS

Our study findings suggest a higher prevalence of lesions in the bones of the lower limbs and pelvis among children with CRMO. Compared with CT scans, FDG PET exhibits superior sensitivity in detecting these lesions.

Bacterial osteomyelitis in pediatric patients: a comprehensive review

Bacterial osteomyelitis, an inflammatory response in the bone caused by microorganisms, typically affects the metaphysis in the skeletally immature. Bacterial osteomyelitis possesses a significant diagnostic challenge in pediatric patients due to its nonspecific clinical presentation. Because the metaphysis is the primary focus of infection in skeletally immature patients, understanding the normal physiologic, maturation process of bones throughout childhood allows to understand the pathophysiology of osteomyelitis. Timely and accurate diagnosis is crucial to initiate appropriate treatment, and prevent long-term sequelae and efforts must be made to isolate the causative organism. The potential causative organism changes according to the age of the patient and underlying medical conditions. Staphylococcus Aureus is the most common isolated bacteria in pediatric pyogenic osteomyelitis whereas Kingella Kingae is the most common causative agent in children aged 6 months to 4 years. Imaging plays a pivotal role in the diagnosis, characterization, evaluation of complications, and follow up of bacterial osteomyelitis. Imaging also plays a pivotal role in the evaluation of potential neoplastic and non-neoplastic mimickers of osteomyelitis. In children, MRI is currently the gold standard imaging modality when suspecting bacterial osteomyelitis, whereas surgical intervention may be required in order to isolate the microorganism, treat complications, and exclude mimickers.

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.

Whole-Body MRI at Initial Presentation of Chronic Recurrent Multifocal Osteomyelitis, Juvenile Idiopathic Arthritis, Their Overlapping Syndrome, and Non-Specific Arthropathy

(1) Background: Whole-body magnetic resonance imaging (WB-MRI) is central to defining total inflammatory burden in juveniles with arthritis. Our aim was to determine and compare the initial distribution of lesions in the WB-MRI in patients with chronic recurrent multifocal osteomyelitis (CRMO), juvenile idiopathic arthritis (JIA), their overlapping syndrome (OS), and with Non-specific Arthropathy (NA). (2) Methods: This retrospective single center study was performed on an Avanto 1.5-T MRI scanner with a dedicated multichannel surface coil system. A total of 173 pediatric patients were included with the following final diagnoses: CRMO (15.0%), JIA (29.5%), OS (4.6%), and NA (50.9%). (3) Results: Bone marrow edema (BME) was the most common abnormality, being seen in 100% patients with CRMO, 88% with OS, 55% with JIA, and 11% with NA. The bones of the lower extremities were the most affected in all compared entities. Effusion was seen in 62.5% children with OS, and in 52.9% with JIA, and in CRMO and NA, the exudate was sporadic. Enthesitis was found in 7.8% of patients with JIA and 3.8% with CRMO, and myositis was seen in 12.5% of patients with OS and in 3.9% with JIA. (4) Conclusions: The most frequent indication for WB-MRI in our center was JIA. The most common pathology in all rheumatic entities was BME, followed by effusion mainly seen in in OS and JIA. Enthesitis and myositis were less common; no case was observed in NA.

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.

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.

Diagnosis and Treatment of Chronic Non-bacterial Osteomyelitis: A Survey on Current Practices Adopted by Pediatric Rheumatologists in Saudi Arabia

INTRODUCTION

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disease usually managed by pediatric rheumatologists (PRs). There is a need for a consensus treatment plan to minimize the diversity in clinical practice in the diagnosis and management of CNO. In this study, we explored the practice of PRs in Saudi Arabia on the diagnosis and treatment of patients with CNO.

METHODS

This is a cross-sectional study that was conducted among PRs in Saudi Arabia (May to September 2020). A survey was performed among PRs registered in the Saudi Commission for Health Specialties using an electronic-based questionnaire. The survey consisted of 35 closed-ended questions about the diagnosis and management of CNO patients. We explored the approaches adopted by PRs in diagnosing and monitoring the disease activity, their awareness of clinical possibilities that necessitate ordering bone biopsy, and the treatment choices they considered for CNO patients.

RESULTS

We scrutinized data from a total of 77% (n=41/53) PRs who responded to our survey. Magnetic resonance imaging (MRI) was reported as the most frequently used modality in suspected CNO (82%, n=27/33), followed by plain X-ray (61%) and bone scintigraphy (58%). Magnetic resonance imaging of a symptomatic site is the imaging modality of choice for the diagnosis of CNO (82%), Followed by X-ray (61%) and bone scintigraphy (58%). The reasons for performing bone biopsy were unifocal lesions (82%), unusual sites of presentation (79%), and multifocal lesions (30%). The preferred treatment regimens were bisphosphonates (53%), non-steroidal anti-inflammatory drugs alone (43%), or biologics with bisphosphonates (28%). The reasons to upgrade the treatment in CNO included the development of vertebral lesions (91%), the development of new lesions in MRI (73%), and the elevation of inflammatory markers (55%). The disease activity was assessed by history and physical examination (91%), inflammatory markers (84%), MRI of targeted symptomatic site (66%), and a whole-body MRI (41%).

CONCLUSIONS

The approach to diagnosis and treatment of CNO varies among PRs in Saudi Arabia. Our findings provide a background for the development of a consensus treatment plan for challenging CNO patients.

Analysis of whole-body MRI artifacts in a pediatric population with a special emphasis on the effect of hands position

PURPOSE

The purpose of this retrospective study was to determine the prevalence of artifacts on whole-body (WB) magnetic resonance imaging (MRI) examination in pediatric patients and identify their causes.

MATERIALS AND METHODS

A total of 107 pediatric patients who underwent a total of 107 WB-MRI examinations, including short-tau inversion recovery (STIR) and T1-weighted sequences, were included. There were 62 girls and 45 boys with a mean age of 11 ± 3 (SD) years (age range: 2-16 years). WB-MRI examinations were analyzed for the presence of artifacts on STIR and T1-weighted sequences. Artifacts were further assigned to one of eight categories (motion, partial volume, cross-talk, phase sampling, susceptibility, equipment, noise, and "other") and 19 anatomical sites by a 4-year resident. Prevalence of artifacts were analyzed especially according to hands position during the examination for the upper limbs and patients' age. Age was expressed as a binary variable using median age (10 years) as the cut-off value. All qualitative variables were compared using chi-square test.

RESULTS

A total of 3436 artifacts were found. The STIR sequences showed more "noise" artifacts (93/1038; 8.96%) and more "cross-talk" (102/1038; 9.83%) artifacts than T1-weighted sequences (12/1038 [1.16%] and 7/1038 [0.67%], respectively) (P < 0.001 for both). T1-weighted sequences showed more "equipment" (84/1038; 8.09%) and "stair-step" (a subset of "other") (41/1038; 3.95%) artifacts than the STIR sequences (39/1038 [3.76%] and 21/1038 [2.02%], respectively) (P < 0.001 and P = 0.01, respectively). T1-weighted sequences showed fewer artifacts on the wrists when the hands were under the bottom (P = 0.001). T1-weighted sequences showed less "equipment" artifacts when the hands were alongside the body (22/296; 7%) than on the abdomen (48/432; 11%) or under the bottom (14/128; 11%) (P < 0.001). STIR sequences showed more "motion" artifacts when the hands were on the abdomen (54/432; 13%) than alongside the body (30/296; 10%) or under the bottom (15/128; 12%) (P < 0.001). WB-MRI examinations had more "susceptibility" artifacts (38/960; 4%) and more "equipment" artifacts (81/960; 8.4%) in patients older than 10 years than in those under 10 years (23/752 [3.1%] and 42/752 [5.6%]) (P = 0.01 and P < 0.001, respectively).

CONCLUSION

Artifacts on WB-MRI do not affect coronal STIR and T1-weighted sequences equally, so the use of both sequence types appears useful. Hands position should be considered with respect to both diagnostic benefit and safety.

Imaging Osteomyelitis: An Update

BACKGROUND

 Hematogenous osteomyelitis has increased over the past quarter century in frequency, virulence, and degree of soft-tissue involvement, bringing about changes in clinical manifestations and management of the disease especially in children that should be reflected in the current imaging approach. Likewise, the global disease burden of diabetes has increased greatly in the same period, compounding the problem of ascertaining osteomyelitis in diabetic foot.

METHOD

 This article provides an updated overview of imaging findings in hematogenous and contiguous osteomyelitis based on the literature and our institutional experience, along with salient features of recent recommendations from expert groups on the diagnostic algorithms and reporting terminology.

RESULTS AND CONCLUSION

 Findings on radiography and especially magnetic resonance imaging (MRI) closely reflect pathophysiology in osteomyelitis, whereby the characteristic involvement of the metaphysis or metaphyseal-equivalents, the formation and subperiosteal extension of intramedullary pus collection, and the development of cloaca, sequestrum, and involucrum are all diagnostic clues. Non-enhancing foci within the medullary bone, the penumbra sign, intra- or extramedullary fat globules, and surrounding soft tissue inflammation or abscesses are among key MRI findings. Diabetic foot is a special condition with characteristic pathophysiologic and imaging features that suggest the likelihood of osteomyelitis and the main differential diagnostic consideration of acute on chronic neuropathic osteoarthropathy with or without osteomyelitis.

KEY POINTS

  · Imaging closely reflects pathophysiology in hematogenous osteomyelitis.. · Acute hematogenous osteomyelitis predominantly involves metaphyses and metaphyseal equivalent sites.. · MRI clues for hematogenous osteomyelitis include central marrow non-enhancement, intra- or extramedullary fat globules, and the "penumbra" sign.. · An increased fluid-sensitive MRI bone signal abutting a soft tissue ulcer, abscess, or sinus tract suggests a high probability of contact osteomyelitis..

CITATION FORMAT

· Aydingoz U, Imaging Osteomyelitis: An Update. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1949-7641.

Whole-body MRI at initial presentation of pediatric chronic recurrent multifocal osteomyelitis and correlation with clinical assessment

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is a diagnosis of exclusion, relying heavily on whole-body magnetic resonance imaging (WB-MRI) for diagnosing and evaluating response to therapy. Information with respect to disease distribution and imaging correlation with clinical disease severity at initial presentation is lacking.

OBJECTIVE

To retrospectively characterize distribution of disease on WB-MRI and to correlate imaging findings with disease severity at initial rheumatology presentation.

MATERIALS AND METHODS

Using a modified version of a recently devised imaging-based scoring system, we evaluated disease distribution and correlation between findings on WB-MRI and clinical disease severity in 54 patients presenting for initial evaluation of CRMO. Symptomatic lesion sites were extracted from chart review and physician global assessment was determined by the consensus of two rheumatologists.

RESULTS

Sites of CRMO involvement evident on imaging at initial presentation had a strong predilection for the pelvis and lower extremities. There was significant correlation between the number of lesions detected on WB-MRI and total clinical severity score at initial rheumatology presentation (P&lt;0.01). However, no other imaging parameter correlated with disease severity.

CONCLUSION

While the overall number of lesions identified on MRI correlates with clinical severity scores at initial imaging, other MR parameters of CRMO lesions may not be reliable indicators of disease severity at initial presentation. Further research is needed to assess whether these parameters are implicated in longitudinal disease severity or overall response to therapy.

Chronic recurrent multifocal osteomyelitis. A narrative and pictorial review

Chronic recurrent and multifocal osteomyelitis (CRMO) is a nonsporadic autoinflammatory disorder. Currently, it is diagnosed based on clinical, radiologic, pathological, and longitudinal data. Numerous aspects should be highlighted due to increased knowledge in imaging and immunology. We emphasize the use of whole-body MRI, which is a non-invasive diagnostic strategy. A literature review was carried out on longitudinal studies. Commonly, the mean age at diagnosis is 11 years, ranging between 3 and 17. The most common sites are the long bone metaphysis, particularly femoral and tibial metaphysis. In addition, the pelvis, spine, clavicle, and mandible may be involved. In long bones, the radiologic appearance can show typical structure, mixed lytic and sclerotic, sclerotic or lytic. It is frequently metaphyseal or juxta-physeal, with hyperostosis or periosteal thickening. The involvement of the vertebral skeleton is often multifocal. Therefore, whole-body MRI is essential in identifying subclinical lesions. CRMO is a polymorphic disorder in which whole-body MRI is beneficial to demonstrate subclinical edema. Vertebral collapse requires long-term monitoring.

Chronic nonbacterial osteomyelitis in children: a multicentre Belgian cohort of 30 children

BACKGROUND

To evaluate clinical characteristics, imaging findings, therapeutic approach and outcome of paediatric patients with Chronic Non-Bacterial Osteomyelitis (CNO).

METHODS

Retrospective review of 30 children diagnosed with CNO at two tertiary care centres in Belgium. Imaging data were evaluated by blinded paediatric radiologists.

RESULTS

Mean age at onset was 10.3 years and mean age at diagnosis was 11.7 years. Bone pain was the leading symptom (29/30 patients). Out of 180 symptomatic lesions, 131 were confirmed on MRI as hyperintense geographic lesions on STIR images at the metaphysis and epiphysis adjacent to growth plates of tubular bones. The most common sites of involvement were the lower limbs, spine, sternoclavicular joint and humerus. For nearly half of the patients (14/30) monotherapy with NSAIDs was sufficient to obtain remission. The remaining 16 patients received second-line therapy: bisphosphonates (n = 15/30), disease-modifying antirheumatic drugs (n = 7/30), etanercept (n = 4/30) and tocilizumab (n = 1/30). Remission was reached after a mean time of 37.6 months in 26/30 patients. The prognosis was worse for patients with spinal involvement, resulting in more long-term sequelae.

CONCLUSIONS

We present a multicentre paediatric cohort of 30 CNO patients. A typical pattern of bone involvement could be found on MRI. NSAIDs were administered as first-line treatment. Second-line strategies included bisphosphonates, corticosteroids, methotrexate, etanercept and tocilizumab.

TRIAL REGISTRATION

Retrospectively registered. Registratienummer EC KUL: MP018023.

Whole-body magnetic resonance imaging findings and patterns of chronic nonbacterial osteomyelitis in a series of Greek pediatric patients

Background:

Chronic nonbacterial osteomyelitis (CNO) is a pediatric autoinflammatory disorder presenting with sterile inflammatory bone lesions. Whole-body MRI (WBMRI) has most recently emerged for disease assessment, but data are limited.

Purpose:

The purpose is to evaluate the imaging findings and patterns of CNO on WBMRI in a series of Greek pediatric patients.

Material and Methods:

Whole-body magnetic resonance imaging studies of all children with documented CNO, performed in a single tertiary center, were retrospectively reviewed. WBMRI included coronal T1 and short-tau inversion recovery (STIR), whole spine sagittal STIR, and ankle/foot sagittal STIR images. High signal intensity lesions on STIR images corresponding to bone marrow edema were recorded. The SPSS v.20 statistical package was used for descriptive statistics.

Results:

Twenty children were included (mean age: 12, range: 6–16 years) with 1–31 lesions (mean: 11.8) on WBMRI. Two children had unifocal disease localized at the clavicle, three paucifocal (1–4 lesions), and 15 multifocal bone involvement. All but two children presented with ankle pain and exhibited lesions at the bones of the ankle joint (90%) followed by the knee (50%) and pelvis (10%). The tibia was the most frequently affected bone (70%) followed by calcaneus (60%), fibula (50%), femur (45%), talus, and metatarsals (45%). No lesions in the cervical, thoracic, lumbar spine, and mandible were documented. Only small sacral lesions were seen in 25% of patients with the extensive peripheral disease. Bilateral metaphyseal and epiphyseal involvement with transphyseal extension were common, but the periosteal reaction and well-defined lesion margins were rare.

Conclusion:

Frequent involvement of the foot and ankle and paucity of substantial spinal involvement were seen in Greek pediatric patients with CNO.

MRI in the Diagnosis and Treatment Response Assessment of Chronic Nonbacterial Osteomyelitis in Children and Adolescents

PURPOSE OF REVIEW

To explain the central role of magnetic resonance imaging (MRI) in the diagnosis and follow-up of chronic nonbacterial osteomyelitis (CNO) in children and adolescents, centering on practical technical aspects and salient diagnostic features.

RECENT FINDINGS

In the absence of conclusive clinical features and widely accepted laboratory tests, including validated disease biomarkers, MRI (whether targeted or covering the entire body) currently plays an indispensable role in the diagnosis and therapy response assessment of CNO. Whole-body MRI, which is the reference imaging standard for CNO, can be limited to a short tau inversion recovery (STIR) coronal image set covering the entire body and a STIR sagittal set covering the spine, an approximately 30-min examination with no need for intravenous contrast or diffusion-weighted imaging. The hallmark of CNO is periphyseal (metaphyseal and/or epi-/apophyseal) osteitis, identified as bright foci on STIR, with or without inflammation of the adjacent periosteum and surrounding soft tissue. Response to bisphosphonate treatment for CNO has some unique MRI findings that should not be mistaken for residual or relapsing disease. Diagnostic features and treatment response characteristics of MRI in pediatric CNO are discussed, also describing the techniques used, pitfalls encountered, and differential diagnostic possibilities considered during daily practice.

Chronic Nonbacterial Osteomyelitis: Insights into Pathogenesis, Assessment, and Treatment

Chronic nonbacterial osteomyelitis, or its most severe form, chronic recurrent multifocal osteomyelitis, is an autoinflammatory bone disease that causes skeletal inflammation characterized by bone pain and swelling that primarily affects children. It is a diagnosis of exclusion and its clinical presentation may mimic underlying infectious processes and malignancy. Clinical suspicion for this diagnosis and timely referral to pediatric rheumatology is crucial to achieve earlier diagnosis, appropriate treatment, and improved quality of life of affected patients and families. This article focuses on recent insights into the pathogenesis of chronic nonbacterial osteomyelitis and outlines recent advances and ongoing research.

Imaging in non-bacterial osteomyelitis in children and adolescents: diagnosis, differential diagnosis and follow-up-an educational review based on a literature survey and own clinical experiences

Background

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disorder affecting children and adolescents. Previously classified as a rare disease, recent studies suggest a higher incidence of the disease. CNO may develop into the clinical presentation of chronic recurrent osteomyelitis (CRMO) with high relapse rate and multifocality.

Main body

Diagnosis of CNO/CRMO is often delayed, with implications for disease severity and relapse rate. This can be significantly improved by knowledge of the disease entity and its characteristics. Imaging plays a key role in diagnosis, differential diagnosis and therapy monitoring. Magnetic resonance imaging (MRI) has several advantages compared to other imaging methods and is increasingly applied in clinical studies. Recent studies show that a whole-body (WB) coverage (WB-MRI) without contrast agent administration is a rational approach. This educational review is based on a systematic analysis of international peer-reviewed articles and presents our own clinical experiences. It provides an overview of disease entity, incidence and clinical diagnosis. The role of imaging, especially of whole-body MRI, is discussed in detail. Finally, practical advice for imaging, including flowcharts explaining when and how to apply imaging, is provided.

Conclusion

Knowing the specifics of CNO/CRMO and the importance of MRI/whole-body MRI allows rapid and efficient diagnosis as well as therapy support and helps to avoid irreversible secondary damage.

Updates and Advances: Pediatric Musculoskeletal Infection Imaging Made Easier for Radiologists and Clinicians

Infants and children often present with a wide range of musculoskeletal (MSK) infections in daily clinical practice. This can vary from relatively benign superficial infections such as cellulitis to destructive osseous and articular infections and life-threatening deep soft tissue processes such as necrotizing fasciitis. Imaging evaluation plays an essential role for initial detection and follow-up evaluation of pediatric MSK infections. Therefore, a clear and up-to-date knowledge of imaging manifestations in MSK infections in infants and children is imperative for timely and accurate diagnosis that, in turn, can result in optimal patient management. This article reviews an up-to-date practical imaging techniques, the differences between pediatric and adult MSK infections, the spectrum of pediatric MSK infections, and mimics of pediatric MSK infections encountered in daily clinical practice by radiologists and clinicians.

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

Epiphyseal lymphoid infiltrates of the knee in adolescents

We present three adolescents with focal lesions of the distal femur that were shown to be benign aggregates of small lymphocytes and plasma cells of unknown origin. The patients were within the age of 12 and 14 years. All lesions presented with similar MRI findings and provided the same histopathological findings in the biopsy. Although all lesions increased in size, only one patient remained symptomatic and underwent subsequent tumor resection. To our best knowledge, tumor or pseudotumoral epiphyseal lymphoid infiltrates as seen in these three patients have not previously been described. We recommend a biopsy to rule out a malignant tumor or an infection. Observation, without further invasive testing in asymptomatic patients, is recommended until the resolution of the lesions. However, if a lesion becomes symptomatic, surgical resection should be considered.

Comparing children and adults with chronic nonbacterial osteomyelitis

PURPOSE OF REVIEW

To describe the main clinical differences of children and adults with chronic nonbacterial osteomyelitis (CNO).

RECENT FINDINGS

CNO is a severe systemic autoinflammatory syndrome characterized by multiple bone lesions because of inflammatory osteitis. Delay to diagnosis of CNO can lead to functional impairment, fractures, and chronic pain. Key clinical aspects and disease patterns differ in children and adults, including onset and time to diagnosis, symptom localization, associated comorbidities (i.e. skin, joints), bone lesion distribution pattern, and treatment approach. Novel biomarkers, such as urine N-terminal telopeptide in children and serum IgG4 in adults, are being studied for possible future use in improving diagnosis and guiding treatment. Despite recent advances in our understanding of CNO, many children and adults have a high disease burden and poor long-term outcomes. Recent findings suggest that adults with CNO tend to have a more chronic disease course and are less likely to achieve remission in follow-up.

SUMMARY

The clinical presentation of CNO differs in children and adults, highlighting the importance of these key features for the accurate diagnosis and early treatment in CNO.

[Pediatric bone marrow alterations]

The age-dependent development of the bone marrow follows a constant pattern and has an impact on the localization and morphology of various bone marrow processes. Physiological, reactive and benign bone marrow alterations must be differentiated from inflammatory or malignant infiltrations. In many cases, a specific age distribution pattern and typical morphological characteristics in magnetic resonance imaging (MRI) enable a diagnostic classification. The only adequate imaging modality that can provide information about the bone marrow composition is MRI.

Biological therapy in refractory chronic nonbacterial osteomyelitis: A case series of 19 patients

INTRODUCTION

Chronic non-bacterial osteomyelitis (CNO) represents an autoinflammatory bone disorder. Currently there are no standardized diagnostic or treatment guidelines. The objective of the study is to describe our experience with biological therapy in children with the disease.

METHODS

Retrospective chart review of patients with CNO treated with biological therapy followed at two tertiary hospitals from January 2007 to April 2020. Biologicals were started in most patients due to persistent disease activity after receiving standard therapy with at least 2 drugs (NSAIDs and corticosteroids and/or pamidronate).

RESULTS

Twenty-five patients were diagnosed with CNO. Out of those, 19 patients (15 females) failed conventional therapy. The mean age at diagnosis was 8.8±2.9 years and the mean diagnostic delay was 6.9±8.3 months. All patients presented with bone pain and 6/19 also had fever. The most frequently affected bones were femur (9 patients), followed by clavicle, tibia and vertebrae (6, 6 and 5 patients respectively). Nine children had skin lesions. C-reactive protein was elevated in 13/19 patients (mean 20.2mg/L±11.7) and ESR in 16/19 (mean 48mm/h±29). All patients received nonsteroidal anti-inflammatory drugs, 15/19 pamidronate, 10/19 corticosteroids and 19 anti-TNF-therapy. At the last follow-up visit, 10/19 patients were still on biological therapy (8 adalimumab, 2 infliximab) and 18 out of 19 remained asymptomatic. In regards to adverse effects, one patient receiving infliximab developed S. aureus osteomyelitis and another cutaneous leishmaniosis.

CONCLUSIONS

This research emphasizes that anti-TNF-therapy represents an effective and safe alternative for patients with CNO refractory to conventional treatments.

The Many Faces of Pediatric Chronic Recurrent Multifocal Osteomyelitis (CRMO): A Practical Location- and Case-Based Approach to Differentiate CRMO From Its Mimics

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease of childhood and adolescence characterized by episodic bone pain. Diagnosis relies heavily on whole-body MRI and is made by excluding a wide variety of other disorders with overlapping imaging features, depending on location, marrow distribution, and the presence or absence of multifocality. We present an overview of the clinical and imaging features of CRMO and, through various clinical scenarios, provide tips for tailoring the differential diagnosis based on location and distribution of encountered abnormalities. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 3.