Expression of HER-2/neu receptor protein in adrenal tumors.

The HER-2/neu protein is overexpressed in many human carcinomas obtained from different tissues and may represent a useful target for therapy with the commercially available monoclonal antibody trastuzumab (herceptin). Novel therapeutic options are needed for metastasized adrenocortical cancer. Therefore, we studied expression of the HER-2/neu cell surface receptor protein using three different antibodies in 12 adrenal adenomas, 17 adrenocortical carcinomas and 5 pheochromocytomas. Normal adrenals (n = 5) served as controls. One adenoma showed very weak membranous immunostaining with the Dako antibody, two others showed a nonspecific cytoplasmic staining pattern. A nonspecific reaction in the cytoplasm was demonstrable in seven carcinomas with the Novocastra antibody. In all pheochromocytomas, a granular intracytoplasmic and, rarely, slightly membranous immunostaining with the Dako antibody was found. From our data we conclude that specific and significant membranous immunostaining indicating strong overexpression (grade 3) of HER-2/neu protein is not present in adrenocortical tumors. The granular cytoplasmic immunostaining of the medulla may be helpful for differentiation of adrenocortical tumors from pheochromocytomas.