Metastatic adenocarcinoma. A case report demonstrating bullous pemphigoid antigen in the tumor.

A case of metastatic adenocarcinoma in the skin of the thigh with an unconfirmed origin is described. Bullous pemphigoid antigen, which is present in the normal basement zone of stratified epithelia, was haphazardly present in the basement membrane zone of the aggregated tumor cells and within the cytoplasm of some cells. This finding indicates that metastatic malignant epithelial cells may produce bullous pemphigoid antigen in the alternative environment, especially if situated in the skin.