Early Gastric Carcinoma with Hepatoid Differentiation: Report of a case with histotopographic analysis

ABSTRACT

A 56-year-old man received subtotal gastrectomy for an early gastric carcinoma type IIa+IIc with submucosal invasion. The tumor was made up of mixed papillo-tubular adenocarcinoma and solid carcinomatous portion, the latter comprising approximately four-fifths of the total tumor mass. The solid portion was confined within the submucosa and revealed a mixture of trabecular, compact and pelioid patterns of large polyhedra cells, resembling hepatocellular carcinoma of the liver(Edmondson-Steiner grade 2). Sinusoid-like vascular stroma of classical trabecular hepatocellular carcinoma intervened the tumor cell nests but was not associated with endothelial-cell lining. Immunohistochemical stainings with alpha-fetoprotein and alpha1-antitrypsin gave a strong reactivity in those areas of hepatoid differentiation and in the adjacent minute portion of adenocarcinoma. The findings suggest that a portion of gastric carcinoma may transdifferentiate into cells with hepatoid features along the line of endodermal lineage.