Chronic Nonbacterial Osteomyelitis in Children

Abstract

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.

Keywords: DIRA; Majeed syndrome; PAPA syndrome; SAPHO; auto-inflammatory bone disease; chronic nonbacterial osteitis; chronic nonbacterial osteomyelitis (CNO); chronic recurrent multifocal osteomyelitis (CRMO); monogenic.

Figure 1

Proposed schematic decisional algorithm for patients with unifocal/multifocal osteoarticular pain. CBC—Complete blood count, CRP—C-reactive protein, ESR—Erythrocyte sedimentation rate, LDH—Lactate dehydrogenase, CPK—Creatine phosphokinase, ANA—Antinuclear antibodies, ENA—Extractable nuclear antigen antibodies panel, US—Ultrasound, MRI—Magnetic resonance imaging, CT—Computed tomography, CNO—Chronic non-bacterial osteomyelitis, CRMO—Chronic recurrent multifocal osteomyelitis, NSAID- Non-steroidal anti-inflammatory drug.