Encapsulated hepatocellular carcinoma: radiologic findings and pathologic correlation.

The encapsulated form of hepatocellular carcinoma (HCC) is a pathologic subtype that has been found to occur with variable frequency in typical HCC in Japanese radiological, surgical, and autopsy series. It is well-differentiated tumor that tends to grow slowly and noninvasively, and has a better prognosis than other gross forms of HCC. Among the 73 cases of typical HCC in patients of non-Asian extraction in our files, 11 could be positively identified as encapsulated based on strict pathological criteria. The purpose of this study was to review the radiographic appearance of these encapsulated tumors. Radiographically, the tumors demonstrated a hyperdense rim in 5 of 9 cases with postinfusion computed tomography scans, an anechoic halo in 4 of 6 cases with ultrasonograms, and an avascular rim on the capillary phase in 5 of the 8 cases with angiograms. Encapsulated HCC can be found in non-Asian patients, and the radiographic and pathologic findings are similar to the descriptions in the Japanese series.