Familial Mediterranean fever with pseudo-septic arthritis: A case report and review of the literature.

INTRODUCTION Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease resulting from mutations of the MEFV gene. The disease is characterized by recurrent attacks of abdominal pain and fever. Most FMF patients develop arthritis at some point in their life usually manifesting as self-limiting mono-arthritis. On very rare occasions, arthritis in FMF can mimic septic arthritis (pseudo-septic arthritis) with very similar clinical and laboratory findings. CASE PRESENTATION We report a case of a young male patient who presented with recurrent attacks of prolonged mono-arthritis. For two years, he had undergone multiple admissions and operations for drainage of suspected septic joints. The synovial aspiration showed culture negative pus with very high synovial white blood cell counts highly suggestive of septic arthritis. The patient was later found to have FMF based on homozygous M694V mutation of the MEFV gene. He was treated with colchicine monotherapy with a quick improvement of the arthritis and later good control of his disease. Literature review showed very few case reports with similar presentation most of which responded well to colchicine. CONCLUSIONS FMF can mimic septic arthritis resulting in unnecessary expensive and invasive interventions and prolonged courses of antibiotics. Pseudo-septic arthritis is usually associated with M694V homozygous mutation and can complicate FMF at any time throughout the disease course. It is important to consider FMF in the differential diagnosis of septic arthritis particularly with a family history of FMF and in patients from communities with high prevalence of MEFV gene mutation.