Hepatocyte nuclear factor 4A expression discriminates gastric involvement by metastatic breast carcinomas from primary gastric adenocarcinomas.

Breast carcinomas sometimes metastasize to the stomach, and the histopathologic distinction of such metastases from primary gastric adenocarcinomas is often difficult. We characterized the clinicopathologic features of 21 breast carcinomas that had metastasized to the stomach and examined the use of a panel of antibodies, including hepatocyte nuclear factor 4A, for distinguishing the metastases from primary gastric diffuse-type adenocarcinomas. Histologically, all the metastatic breast carcinomas showed a poorly differentiated and/or signet ring cell morphology.