Musculoskeletal Ultrasound of the Ankles in Erysipelas-like Erythema of Familial Mediterranean Fever

Inclusion Criteria: * Age ≥ 18 years old * Patient followed by the National reference center for autoinflammatory diseases and inflammatory amyloidosis (CeRéMAIA) at Tenon Hospital in Paris * Patient with a diagnosis of FMF based on Livneh criteria and supported by 2 pathogenic MEFV mutations * Patient with unilateral ankle ELE for less than 24 hours and whose diagnosis is confirmed a posteriori by its spontaneous resolution in 72 hours * Patient affiliated or entitled to an affiliation to a social security system * Provision of informed consent Exclusion Criteria: * Incapacity to answer questions, express him(her)self clearly, or collaborate with the performance of the musculoskeletal ultrasound * Previous surgery, significant trauma, destructive arthropathy, and any other pathology affecting the musculoskeletal structures of the ankle and thus influencing its sonographic examination * Previous diagnosis of gout * Current pregnancy * Patient deprived of liberty or under legal protection