Iliopsoas Muscle Involvement due to Granulomatosis with Polyangiitis.

Abstract

Swollen iliopsoas muscle has a broad differential diagnosis, including infection, neoplasm, hemorrhage, sarcoidosis, and vasculitis including granulomatosis with polyangiitis (GPA)1. A previously healthy 42-year-old man presented to our clinic with 4 weeks of fever, malaise, left orbital puffiness, and low back pain. Laboratory tests showed normal renal and hepatic function and C-reactive protein (CRP) level of 7.45 mg/dL. Blood cultures were negative. There had been no response to antibiotics. Magnetic resonance imaging and computed tomography (CT) revealed retro-orbital mass (Figure 1A …