Omental Hibernoma Revealed by 18 F-FDG PET/CT

Hibernomas are "pseudolipomas" originating from remnants of fetal brown adipose tissue. These rare benign tumors may occur throughout the body but most commonly in the thigh, shoulder, back, and neck, and are rarely found in the abdominal cavity, retroperitoneum, breast, bones, scrotum, and perirectum. We present a case of a 58-year-old woman with a known mediastinal mass, who was incidentally found to have a very FDG-avid fat-containing lesion in the omentum abutting the stomach. Subsequent endoscopic ultrasound-guided fine-needle aspiration confirmed hibernoma. The review of the literature shows the location is very unusual.