Immunohistochemical differentiation of metastatic breast carcinomas from metastatic adenocarcinomas of other common primary sites.

To test the possibility of immunohistochemical differentiation of cytostatically treatable metastatic breast carcinomas from other metastatic adenocarcinomas of unknown primary site, we studied a total of 328 metastatic adenocarcinomas including 35 bronchogenic, 26 pancreatic, 25 colonic, 39 gastric, 45 renal, 29 ovarian and 129 breast carcinomas with a panel of 13 commercially available monoclonal antibodies. The expression of gross cystic disease fluid protein 15 and/or oestrogen or progesterone receptors had a sensitivity of 0.83, a specificity of 0.