Pathological study of small hepatocellular carcinoma: frequency of their invasion.

We studied the pathological findings in 28 small hepatocellular carcinomas (less than 5 cm in diameter), especially the mode of invasion. Seventeen of the 28 lesions were encapsulated. Capsular invasion was present in 14 of the 17 encapsulated tumours. Vascular invasion was found in 12 of the 28 tumours. The small hepatocellular carcinoma, even when encapsulated, frequently invaded blood vessels and adjacent liver tissue, in spite of frequent vascular invasion, distant metastasis was seen in only 1 of the 28 tumours.