Diagnostic challenge in a Tunisian patient with Familial Mediterranean Fever, sacroiliitis and coxitis

Introduction: Familial Mediterranean Fever (FMF) is a hereditary auto inflammatory disease. The most common joint attack is an acute large joint monoarthritis most often affecting the knee or hip and lasting for several days. Rarely, a more protracted arthritis may occur. Case report: Herein, we describe a 47-year-old man with FMF in whom a few years elapsed before a definitive diagnosis could be made. The patient presented, since the age of 25, with a history of recurrent episodes of fever, abdominal pain, bloody diarrhea and intermittent attacks of acute bi-arthritis of hips. At the age of 40, he was referred under the suspicion of Spondylarthritis (SpA); in view of an inflammatory back pain, talalgia and bilateral coxitis. The result of blood tests suggested the presence of a high level of inflammation without leukocytosis. Human leukocyte antigen (HLA-B27) was negative. X-ray and computerized tomography of the pelvis showed an overall bilateral joint space narrowing of the hips and grade 3 bilateral sacroiliitis. During the hospitalization, he developed an acute episode of fever, abdominal pain and muscle contracture, spontaneously resolved in 12 h. We suspected FMF based on the clinical course and family history, as one of his brothers had suffered similar abdominal crises since childhood. Molecular analysis for FMF was done, and demonstrated a homozygote mutation of M649V. A definitive diagnosis of FMF was then made. Oral administration of colchicine was followed by a remission. Conclusion: Clinicians should consider FMF with sacroiliitis and coxitis in the differential diagnosis of spondyloarthritis