Medium-Vessel Vasculitis on FDG-PET/CT at Initial Presentation and Relapse.

A 76-year-old man presented with morning facial edema, forearm induration, testicular pain, and a major inflammatory syndrome. Contrast-enhanced CT was inconclusive. Conversely, FDG-PET/CT showed pathological uptake of medium-vessels, particularly in the right arm and facial soft tissues, leading to the diagnosis of medium-vessel vasculitis. Symptoms vanished after methotrexate and corticosteroid initiation. While undergoing progressive corticosteroid dose reduction, he presented with lower limb myalgia. A second FDG-PET/CT confirmed the relapse, with extensive uptake of the intermuscular perforating arteries of the limb. This clinical report illustrates the good correlation between clinical symptoms and FDG-PET/CT findings, in these challenging to diagnose vasculitides.