Expression of mullerian inhibiting substance, CD99 and HEA125 in ovarian tumors

Objective: The expression of Mullerian inhibiting substance (MIS), CD99 (MI C-2 gene product), and HEA125 in ovarian tumors is potentially useful for d iagnostic purposes. Methods: We studied the expression of MIS, CD99, and an epithelial cell-ass ociated antigen recognized by antibody HEA125 in a series of 179 ovarian tu mors using monoclonal or polyclonal antibodies and standard immunohistochem ical techniques. Results: MIS was consistently detected in primary and metastatic sex cord t umors with annular tubules (SCTAT) (n=9). 3 of 9 adult granulosa cell tumor s (AGCT) 4 of 8 juvenile granulosa cell tumors (JGCT), 3 of 9 Sertoli cell tumors (SCT), 2 of 2 unclassified sex cord tumors, 2 of 7 steroid cell tumo rs, 1 of 1 gonadoblastoma (sex cord cells positive, germ cells negative), 3 of S female adnexal tumors of probable wolffian origin (FATPWO), and 2 of 4 small cell carcinomas of the hypercalcemic type (SCCHCT) were also MIS po sitive. In contrast, 9 thecomas, 10 fibromas, 10 fibrosarcomas, S sclerosin g stromal tumors (SST), and 6 Sertoli-Leydig cell tumors (SLCT) were MIS ne gative. All 11 primary and metastatic JGCT were CD19 positive. In addition, 1 of 13 AGCTs, 3 of II thecomas, 3 of II SSTs, 3 of 11 SCTs, 2 of 10 SLCTs , 2 of 12 SCTATs, 1 of 1 gynandroblastoma, 1, of 2 unclassified sex cord tu mors, and 4 of 12 SCCHCTs were also CD99 positive. However, 11 fibromas, 10 fibrosarcomas, 9 steroid cell tumors, 5 gonadoblastomas, and 10 FATPWOs we re CD99 negative. Likewise, except for weak focal CD99 immunostaining in 1 of 3 yolk sac tumors (YST), all 16 remaining germ cell tumors and all 18 bo rderline or malignant epithelial-stromal tumors were negative. HEA125 immun oreactivity was detected in 2 of 11 thecomas, 1 of 11 SCTs, 4 of 10 SLCTs, 1 of 2 unclassified sex cord tumors, 1 of 10 FATPWOs, 4 of 12 SCCHCTs as we ll as in most germ cell tumors and epithelial-stromal tumors. 13 AGCTs, 11 JGCTs, 11 fibromas, 10 fibrosarcomas, 11 SSTs, 12 SCTATs, 1 gynandroblastom a, 9 steroid cell tumors, and 5 gonadoblastomas were HEA125 negative. Conclusion: Our findings indicate that MIS is a marker of sex-cord differen tiation and may be useful as a serum tumor marker for certain sex cord tumo rs, especially SCTAT. Although the detection of MIS and CD99 in some SCCHCT s and FATPWOs might argue in favor of a sex cord origin, the histogenesis o f these tumors remains unclear. Although inhibin-cr has previously been sho wn to be a more sensitive marker of sex-cord differentiation, a panel of im munohistochemical markers including MIS, CD99 and HEA125 may be helpful in the differential diagnosis of certain ovarian neoplasms.