Relationship of angiographic finding with neovascular structure detected by immunohistochemical staining of α-smooth muscle actin in small hepatocellular carcinoma

To elucidate the relationship between angiographic features and histological findings, an immunohistological study of ex-smooth muscle actin was performed in 106 patients with small hepatocellular carcinoma. Arterial dominance or portal blood paucity were found in 73 patients (68.9%) on digital subtraction angiography, 88 (83.0%) on computerized tomographic arterial portography and 87 (82.1%) on carbon dioxide-enhanced ultrasonography. Among 73 patients with hypervascularity on angiography, 57 (78.1%) had thick-walled, nuclei-rich and slender-shaped vessels (type II), eight (11.0%) had thin-walled, nuclei-poor and oval-shaped vessels (type I) and the remaining eight had a mixed type of II and I. Conversely, among 33 patients without hypervascularity, five (15.2%) had a type II, 21 (63.6%) had a type I, five had a mixed type and two had no positive vessel. Tumour size, histological classification and amount of non-triadal vessels were also associated with the angiographic appearance of the rumours. Among varied aspects of the cancer including tumour size, tumour multiplicity, microscopic portal invasion, histological classification, amount of alpha-smooth muscle actin-positive vessels and shape of alpha-smooth muscle actin-positive vessels, multivariate logistic regression analysis demonstrated that the shape of alpha-smooth muscle actin-positive vessels was solely associated with angiographic hypervascularity independently (P < 0.0001). Although the existence of non-triadal vessels characterized hepatocellular carcinoma, angiographic hypervascularity was closely associated with the type II vessel. A morphological change of non-triadal vessel from type I to type II was considered to occur in an early stage of hepatocellular carcinoma.