Hepatoid adenocarcinoma of the stomach.

A 54-year-old man presented to his doctor with hematemesis and was found at endoscopy to have an ulcerated lesion in his stomach. A computed tomography scan was performed and revealed a mass in the fundus of the stomach. Multiple other lesions were identified in the liver, lungs, retroperitoneal space, and mesentery. Gross examination showed two separate gastric lesions containing nests and single cells with mucin intermixed with sheets of tumor cells with abundant eosinophilic cytoplasm invading throughout the wall of the stomach. Immunohistochemical studies were performed and the cells were positive for hepatocyte, MOC 31, cytokeratin A1/A3, and CK 7, and were negative for CK 20, alpha-fetoprotein, and thyroid transcription factor. The histologic features together with the immunohistochemical findings were diagnostic of a hepatoid adenocarcinoma of the stomach. Hepatoid adenocarcinoma is a rare tumor associated with a very poor prognosis. Immunohistochemical studies may help to identify the characteristic features of hepatoid differentiation and prevent mistaking this tumor for other types of carcinoma.