Venous involvement in islet cell tumors of the pancreas.

Peripancreatic venous abnormalities were demonstrated angiographically in 10 patients with islet cell tumor: six nonfunctioning, two gastrin-producing, one glucagon-producing, and one pancreatic polypeptide-producing. Venous involvement recognized included venous occlusion, venous encasement, and intraportal tumor growth. Seven patients had islet cell carcinoma with hepatic metastases while the other three had benign tumors. Three patients had arteriographic evidence of intraportal tumor growth with the "thread and streaks" sign, similar to that of portal venous extension of hepatocellular carcinoma.