Isolated Immunoglobulin G4-Related Disease of Nasal Septum and Maxilla: Diagnosis and Follow-up With 18F-FDG PET/CT.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic inflammatory condition that can manifest in atypical locations. We present the case of a middle-aged woman presenting with isolated IgG4-RD of left maxilla and nasal septum, confirmed with F-FDG PET/CT. She achieved complete metabolic response with multiple pharmacologic treatment, but 1 year later, she experienced local relapse, and FDG PET/CT found new additional lesions in humeral vasculature and lungs. This case illustrates the usefulness of FDG PET/CT for initial evaluation and monitoring of IgG4-RD with unusual nasomaxillary involvement.