Immunohistochemical Analysis of Peritoneal Mesothelioma and Primary and Secondary Serous Carcinoma of the Peritoneum

The role of immunohistochemical markers in distinguishing peritoneal mesothelioma from primary or metastatic serous papillary carcinoma of the peritoneum was evaluated. We immunostained 20 peritoneal mesotheliomas (from 14 men and 6 women), 14 primary peritoneal carcinomas, and 14 metastatic serous ovarian carcinomas with a panel of 16 antibodies. Positive staining for calretinin was identified in 17 (85%) of 20 mesotheliomas, but all carcinomas were negative. Positive staining for Ber-EP4 was identified in 27 (96%) of 28 carcinomas and in 2 (10%) of 20 mesotheliomas. Estrogen receptors were positive in 26 (93%) of 28 carcinomas, and progesterone receptors were positive in 8 (29%) of 28 carcinomas. All mesotheliomas were negative for estrogen and progesterone receptors. The other antibodies evaluated were insufficiently sensitive and/or specific to be diagnostically useful. In conjunction with calretinin and Ber-EP4, estrogen and progesterone receptors are useful discriminatory markers for distinguishing peritoneal mesothelioma from primary or metastatic serous carcinoma.