A Case of Chronic Recurrent Multifocal Osteomyelitis (CRMO).

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare but underdiagnosed, severe inflammatory bone disease that primarily affects children. It's typically characterized by bone pain, especially within the metaphysis of long bones, clavicles, and vertebrae, but it can present in any bone and with varied presentation, including extraosseous symptoms that may be associated with other autoimmune/inflammatory diseases. Chronic recurrent multifocal osteomyelitis is a sterile bone disease that does not typically have an infectious source. Its pathogenesis involves the dysregulation of the innate immune system via upregulation of cytokines, inflammasomes, and osteoclastic properties. Diagnostic testing is nonspecific and includes X-ray and MRI, bone biopsy, inflammatory markers, and autoimmune markers. Chronic recurrent multifocal osteomyelitis is established by the diagnosis of exclusion. First-line treatment is nonsteroidal anti-inflammatory drugs (NSAIDs); if vertebral involvement is present, a bisphosphonate is typically added. This case report emphasizes the importance of considering CRMO as a differential diagnosis of multifocal bone pain in children.