Fever of unknown origin in the outpatient setting: A retrospective analysis of 30 cases of familial Mediterranean fever.

BACKGROUND: In Japan, familial Mediterranean fever (FMF) is a rare cause of fever of unknown origin (FUO). However, we experienced an extraordinary number of FMF cases over 3 years. This suggests that many patients with FMF remain misdiagnosed in Japan. This study examines the clinical picture of FMF to assist Japanese clinicians in daily practice dealing with FUO.

PATIENTS AND METHODS: Three years of medical records were reviewed, and 38 patients with FMF or suspected FMF were collected from our patient database. We applied the Tel-Hashomer criteria to those patients.

RESULTS: Of the 38 patients, 30 were classified as having FMF in this investigation. The mean patient age was 27.8 years. MEFV gene mutations were detected in 14 patients. Three cases were colchicine-resistant.

CONCLUSION: Clinicians should recognize the pattern of short, spontaneously resolving attacks of fever with fever-free intervals, especially when they see patients with recurrent FUO in the outpatient setting.