IgG4-related Autoimmune Hepatitis Mimicking Hepatic Malignancy Shown on 18F-FDG PET/CT

We report the ¹⁸ F-FDG PET/CT findings of IgG4-related autoimmune hepatitis mimicking hepatic malignancy in a 52-year-old man. The patient presented with intermittent fever, abdominal pain, and significantly elevated tumor markers. Initial evaluation with contrast-enhanced CT suggested hepatic malignancy. ¹⁸ F-FDG PET/CT demonstrated heterogeneous hepatic FDG uptake and multiregional hypermetabolic lymphadenopathy. Diagnosis was confirmed by cervical lymph node biopsy and a favorable clinical response to glucocorticoid therapy.