Pseudoglandular hepatoid differentiation in endometrioid carcinoma of the ovary simulates oxyphilic cell change

A 42-year-old patient had a stage III ovarian endometrioid adenocarcinoma with areas of hepatoid carcinoma (HC) of clear cell and eosinophilic pseudoglandular type that was difficult to differentiate from endometrioid carcinoma of oxyphilic type and sex cord-stromal tumor. Immunohistochemically, endometrioid adenocarcinoma was positive for CA125, estrogen and progesterone receptors, CAM5.2, cytokeratin (CK) 7 and 19, and vimentin. HC areas were positive for hep par1, polyclonal carcinoembryonic antigens, CD10, alpha-fetoprotein, epithelial membrane antigens, and antimitochondrial antibodies and shared with endometrioid carcinoma focal CK7, and constant positive CK19, CAM5.2, and progesterone receptors. In the differential diagnosis, a hepatic immunophenotype of oxyphilic, mitochondriae-rich areas (demonstrated by antimitochondrial antibodies) was identified by HC specific (hep par1) and characteristic markers: canalicular, cytoplasmic and membranous polyclonal carcinoembryonic antigens, CD10 patterns, and alpha-fetoprotein). Trabecular and clear vacuolated areas of HC resembled luteinized cells of sex cord-stromal ovarian tumors, but the membranous positivity to CAM5.2 supported epithelial (hepatoid) identity. The partial preservation of an endometrioid immunophenotype in HC (positive CK7 and 19 and progesterone receptors) would support an origin from endometrioid carcinoma.