Chronic recurrent multifocal osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare autoinflammatory bone disorder in which lesions, inflammation and pain appear at multiple skeletal sites over time, despite the absence of any actual infecting organism. The name is misleading in that it mimics osteomyelitis, an infectious bone disease, while arising through a non-infectious inflammatory process; it was formerly classified as autoimmune and is now understood as autoinflammatory. Its exact cause is not fully established, though inherited genetic factors are implicated, with mutations in genes including LPIN2 and PSTPIP2 identified in some forms, although the precise role those genes play remains uncertain. CRMO is managed within rheumatology and primarily affects children, most commonly between ages four and fourteen with a median onset around age ten, and occurs about five times more often in girls than boys, though it can also occur in adults. Flares of bone pain and inflammation recur over months or years, and the skin and gastrointestinal tract can also be involved in some patients.