Pseudoglandular hepatocellular carcinoma. A morphogenetic study.

A histopathologic study of pseudoglandular formation was made by observing selected 39 cases of hepatocellular carcinoma (HCC). The pseudoglands were most often derived from the dilatation of bile canaliculi (28/39). The dilated canaliculi were sometimes connected and divided a cell trabecula to give a pseudopapillary appearance. A second type was concerned with tumor cell necrosis and subsequent pseudoglandular formation (6/39). A rare variant similar to papillary carcinoma was also seen in this group. Third, five cases showed microglandular formation in an scirrhous environment thereby resembling cholangiocarcinoma or metastatic adenocarcinomas. Despite these confusing features, the overall tumor histologic features, in particular the existence of a characteristic trabecular growth pattern made it possible to determine all of the cases as HCC. The importance of noticing these variable manifestations of HCC is yet emphasized in regard to differential diagnosis of hepatic tumors. The glandular elements seen in two cases of combined HCC and cholangiocarcinoma differed in that they were positive for mucin staining. In addition, the tumor cells contained mucin-positive intracytoplasmic vacuoles similar to those observed in common mucin producing adenocarcinomas.