Hepatic Involvement of IgG4-Related Disease Presenting as Multiple Hypermetabolic Masses on FDG PET/CT

A 45-year-old man was found with multiple hepatic masses in CT/MR, suggesting liver metastases of unknown origin. F-FDG PET/CT showed several hypermetabolic masses in the liver; patchy increased uptake in the pancreas; and FDG-avid lymph nodes in the neck, axilla, and mediastinum. Histopathology with biopsy revealed enriched IgG4-positive lymphoplasmacytic cells infiltrating in the liver, pancreas, and lymph nodes, which confirmed the diagnosis of IgG4-related disease. The lesions were diminished on follow-up PET/CT 3 months after treatment with prednisone. This case illustrated that multifocal FDG-avid hepatic mass might be the involvement of IgG4-related disease, which should be differentiated from malignancies.