Effect of transcatheter arterial embolization on the boundary architecture of hepatocellular carcinoma.

Daughter nodules and intrahepatic metastases are resistant to conventional transcatheter arterial embolization therapy. To clarify the mechanism of this resistance, the boundaries of hepatocellular carcinomas and their relationship to the blood supply were studied. The boundaries of the hepatocellular carcinomas studied were classified as one of five types: encapsulated, granulation, stromal, replacing, or sinusoidal. The granulation and stromal types had a capsule-like structure, but lacked the hyalinization which is the hallmark of a true tumor capsule. The granulation and stromal types could also be differentiated from the encapsulated type because of their different blood supplies and the differing effects of transcatheter arterial embolization. When barium sulfate was infused into the portal vein, it did not enter into encapsulated tumors, but it entered granulation and stromal type tumors. Small nodules such as daughter nodules and intrahepatic metastases do not have capsules, and so have a blood supply that makes them resistant to conventional transcatheter arterial embolization therapy.