Expanding the Spectrum: a case of Giant cell arteritis encountered in familial Mediterranean fever

Abstract Familial Mediterranean Fever (FMF) is an autoinflammatory genetic disorder causing recurrent fever episodes due to MEFV gene mutations, typically affecting small and medium-sized vessels. We present a 69-year-old male with FMF exhibiting features suggestive of large vessel vasculitis, challenging the conventional understanding of FMF. The patient had an extended fever episode, a self-resolving groin rash, intermittent diarrhea, and a decline in health over six months. A PET scan showed increased uptake in large vessels, especially in the bilateral lower extremities, indicating possible large vessel vasculitis. The patient's positive response to corticosteroid therapy supported an inflammatory etiology. This case underscores the need for a broader differential diagnosis in atypical FMF presentations and suggests further research into the relationship between FMF and large vessel vasculitis.