Tumor thrombus differentiates itself from bland thrombus by its contrast enhancement features on cross-sectional imaging and its intense uptake of F-18 FDG on PET as a result of its hypervascularity and high metabolic neoplastic activity. This PET pattern has been reported in cases of renal cell carcinoma and adrenal cortical carcinoma with invasion of the inferior vena cava. Tumor thrombus may involve the superior mesenteric and portal veins in patients with abdominal or pelvic malignancy. The author presents a case of recurrent pancreatic neuroendocrine tumor with mesenteric and portal venous thrombotic invasion imaged by PET and computed tomography.