Myositis Associated With Eosinophilic Granulomatosis With Polyangiitis Demonstrated by FDG PET/CT.

A 54-year-old woman with a history of adult-onset asthma presented with prolonged fever, rash, joint pain, and hypesthesia. Laboratory findings showed elevated eosinophils (22%). FDG PET/CT demonstrated uptake in consolidations in both lungs, consistent with eosinophilic pneumonia, and revealed systemic myositis with increased uptake (SUVmax 5.5) in muscles, predominantly in the lower extremities. Based on the 2022 ACR/EULAR criteria, she was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA). This case highlights the value of FDG PET/CT in demonstrating eosinophilic pneumonia and in myositis associated with EGPA, suggesting its potential role in diagnosing EGPA in patients with fever of unknown origin.