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

Update on the diagnosis and treatment of CNO in children: a clinician's perspective

Chronic non-bacterial osteomyelitis (CNO) is caused by aseptic inflammation of bones, primarily driven by the innate immune system. CNO may display different clinical presentations (acute vs chronic, uni- vs multifocal) and is accompanied by other inflammatory disorders in up to a third of patients. Once considered a rare disorder, it has become clear that many patients were underdiagnosed. With increasing awareness and the development of total-body MRI protocols, CNO recognition and diagnosis have greatly improved. Our knowledge of the clinical manifestations and outcomes of CNO has been refined in recent years, especially thanks to the recruitment of large international series. Similarly, new insights into the pathogenesis have been gained by the development of mice models and identification of rare monogenic diseases that resemble CNO. Unfortunately, these advances have not been paralleled in the therapeutic management. In the absence of prospective controlled trials, therapeutic strategies still rely on low-level evidence studies. About half of the patients respond to first-line therapies, but a more refractory and/or chronic disease course requires additional treatments. This narrative review aims to provide the practicing physician with an update on CNO pathogenesis, clinical presentation, associated inflammatory conditions, and diagnostic investigations, and includes a concise summary of current therapeutic recommendations.

CONCLUSION

While major progresses have been made in the recognition and management of CNO, significant challenges remain, in particular regarding the treatment of refractory patients, and those with associated inflammatory disorders.

WHAT IS KNOWN

• Many physicians caring for children will encounter patients suffering of (suspected) CNO. CNO diagnosis requires exclusion of numerous conditions included in the differential diagnosis, which may be challenging.

WHAT IS NEW

• We provide an updated review of recent findings in the field CNO, including imaging and diagnostic strategies, associated inflammatory diseases and long-term outcomes data. • We focus particularly on the challenges encountered by clinicians in the diagnosis and treatment of these patients. • We highlight knowledge gaps in the understanding and treatment of CNO, that should stimulate future research.

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.