Immunophenotypic analysis of ovarian and testicular Müllerian papillary serous tumors

Intratesticular Müllerian papillary serous tumors lacking stromal invasion are uncommon neoplasms whose immunophenotypic properties have not been studied extensively. We present such information here and compare it with information from a group of ovarian papillary serous tumors of low malignant potential ("borderline serous tumors") that are morphologically identical. We compared the histologic features of our index case of intratesticular Müllerian papillary serous tumor with those of nine ovarian papillary serous tumors. We then evaluated both the index case and the ovarian tumors with antibodies against carcinoembryonic antigen, LeuM1, CA125, estrogen receptors, progesterone receptors, cytokeratin 7, and cytokeratin 20, by use of established immunohistochemical techniques. The testicular and ovarian tumors were morphologically indistinguishable. The intratesticular Müllerian papillary serous tumor expressed LeuM1, CA125, estrogen receptors, progesterone receptors, cytokeratin 7, and weak cytokeratin 20; carcinoembryonic antigen was not expressed. All of the ovarian papillary serous tumors expressed CA125, estrogen receptors, and cytokeratin 7. Eight of nine expressed progesterone receptors. Five of nine stained with LeuM1. Two of nine were focally weakly positive with cytokeratin 20. LeuM1 expression helps distinguish testicular papillary serous tumors from mesothelial proliferations, which might seem morphologically similar. The immunophenotype of intratesticular and female genital papillary serous tumors is similar; this similarity extends to expression of estrogen and progesterone receptors, which is rare in neoplasms in men, especially among testicular neoplasms.