Isolated Malignant Portal Vein Thrombus in Colon Carcinoma: A Rare Finding on 18F-FDG PET/CECT.

In the absence of hepatic metastasis in abdominal cancers, an isolated malignant portal vein thrombus is very rare. The presence of a malignant thrombus has clinical significance for determining the stage, treatment, and prognosis. 18F-FDG PET/CECT is a noninvasive modality for discriminating between malignant and benign thrombi. We present a case of primary sigmoid colon carcinoma for which 18F-FDG PET/CT showed, in addition to the 18F-FDG-avid primary lesion, an 18F-FDG-avid filling defect in the portal vein, likely malignant thrombus.