Myalgia in familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever and painful episodes of sterile peritonitis, pleuritis and arthritis. Among rare symptoms of the disease, muscular manifestations, first described in 1945, sometimes as one of the main clinical manifestations or as its sole feature should be recognized. We present a patient with FMF in whom severe myalgia were predominant. An 18 year-old Tunisian boy treated with corticosteroids for an "inflammatory myopathy" in another institution was admitted for abdominal pain. FMF was suspected because of a history of paroxysmal abdominal pain with fever from the age of 5 leading two times to laparotomy and one attack of left knee arthritis at the age of 14. FMF diagnosis was confirmed genetically, corticosteroids were tapered and a treatment with colchicine was started. Two years and a half later, he was admitted for severe and incapacitating myalgia of the upper and lower limbs without fever nor abdominal pain that responded well to rest and colchicine. Myalgia was then definitively attached to FMF. Three clinical patterns of myalgia are now well identified in FMF: the spontaneous pattern as observed in our patient, the exercise-induced pattern and the protracted febrile myalgia syndrome. The three patterns differ in the severity of pain, grade of fever and duration of the episode.