The arthritis of familial Mediterranean fever.

Familial Mediterranean fever (FMF) is a disease of unknown etiology and pathogenesis. In addition to fever, arthritis is among its most frequent manifestations. The arthritis of FMF is typically an acute, episodic, self-limited process with no sequelae. The radiographic features of FMF arthritis are usually limited to transient, often severe osteoporosis. Synovial fluid analysis many mimic septic arthritis with very high white blood cell counts; cultures are uniformly negative. The course of FMF is almost always benign, with no residual articular incapacity. Some patients, limited to certain ethnic groups, develop renal amyloidosis. Colchicine therapy modifies the natural history of the disease by decreasing the attack frequency and preventing amyloid deposition. At present, a lipocortin deficiency appears to be the likely candidate for a pathogenic mechanism. An unusual case with dramatic periarticular features (periostitis) and a protracted course with an excellent response to synovectomies is reported here. There is no explanation for the exuberant periarticular bone formation noted in this case, but a variety of recently discovered growth factors may be implicated.