Primary Ovarian High-grade Neuroendocrine Carcinoma With Merkel Cell–like Immunophenotype Arising in a Teratoma

We report a case of an 19-yr-old female with bilateral ovarian teratomas with a high-grade NEC (immunohistochemically positive with chromogranin, synaptophysin, and CD56 and MIB1 proliferation index in excess of 90%) arising within one of these. Although CK20 was negative, the NEC exhibited an immunophenotype suggestive of a Merkel cell carcinoma with diffuse positive staining with FLI-1, SATB2 and neurofilament, markers which are preferentially expressed in Merkel cell carcinoma compared with other NECs. There was also diffuse staining for SALL4. Immunohistochemistry and molecular studies for Merkel cell polyomavirus were negative. Immunohistochemical staining for CK20, FLI-1, SATB2, neurofilament, and SALL4 was performed in 6 additional primary ovarian high-grade NECs; One, 5, 5, 1, and 0 cases were positive for CK20, FLI-1, SATB2, neurofilament, and SALL4, respectively, usually with very focal immunoreactivity. Pathologists should be aware of these potential unexpected staining patterns in ovarian NECs as positivity may result in consideration of other neoplasms.
Source: International Journal of Gynecological Pathology - Category: Pathology Tags: PATHOLOGY OF THE UPPER TRACT: CASE REPORTS Source Type: research