Transitional Cell-like Morphology in Ovarian Endometrioid Carcinoma Morphologic, Immunohistochemical, and Behavioral Features Distinguishing it From High-grade Serous Carcinoma
ABSTRACT Transitional cell-like growth has been reported as a morphologic variant of endometrioid adenocarcinoma in the uterus but is not well-described in the ovary. We report the clinicopathologic features of a series of ovarian endometrioid adenocarcinomas with transitional cell-like morphology, emphasizing the distinction from its mimics, including high-grade serous carcinoma, transitional cell carcinoma, and granulosa cell tumor. Among a cohort of 71 ovarian endometrioid adenocarcinomas surgically staged at our institution, 10 tumors (14%) exhibited transitional cell-like morphology. Patient age ranged from 39 to 79 years (mean, 52 y). Five tumors were stage I, 2 were stage II, and 3 stage III. The tumors ranged from 8.5 to 23 cm, and the transitional cell-like component occupied from 5% to 90% of the overall tumor, with the remainder being conventional endometrioid adenocarcinoma. The most compelling findings to support that this tumor pattern represents a morphologic variant of endometrioid adenocarcinoma are that the transitional cell-like components (1) merged directly and seamlessly with the conventional endometrioid component; (2) contained areas of mature or immature squamous differentiation; (3) lacked WT1 immunoexpression; (4) lacked the characteristic p53/p16 immunophenotype of high-grade serous carcinoma; and (5) did not appear to independently affect patient outcome. Two patients (20%) whose tumor contained transitional cell-like morphology died, whereas 14 patients (23%) lacking this morphology died. Although uncommon, transitional cell-like morphology appears to be a variant growth pattern of ovarian endometrioid adenocarcinoma that does not affect behavior and that should be distinguished from high-grade serous carcinoma and conventional ovarian transitional cell carcinoma.
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ABSTRACT: Ovarian endometrioid adenocarcinomas may have an extremely variable morphologic appearance and mimic a number of other epithelial malignancies as well as nonepithelial tumors. We report the clinicopathologic features of a small series of ovarian endometrioid adenocarcinomas (n=5), 4 of which were received in consultation, which were originally diagnosed as or were suspected to represent serous borderline tumor, with or without a component of low-grade serous adenocarcinoma. The patients were aged between 47 and 74 yr (mean, 60 yr), and all tumors were unilateral and Stage 1C. Serous borderline tumor was suspected on the basis of the predominant architectural pattern with prominent papillary formations consisting of rather bland epithelial cells covering stromal cores which projected into cystic spaces. In all cases, there were areas of typical endometrioid adenocarcinoma, although these foci were minor. Features useful in confirming an endometrioid neoplasm, not all of which were present in every case, were a monomorphous cell population, areas of cytoplasmic clearing, areas of more pronounced nuclear atypia, and mitotic activity than is typical of low-grade serous neoplasms, squamous elements, endometriosis and absent or only focal WT1 immunohistochemical staining. The close mimicry of a serous borderline tumor by an endometrioid adenocarcinoma is a diagnostic pitfall which has not been reported in the literature and represents yet another example of the propensity for ovarian endometrioid adenocarcinomas to mimic other neoplasms. Pathologists should consider an endometrioid adenocarcinoma when faced with a presumed serous borderline tumor with any of the features listed above. Extensive sampling may be of value in revealing more typical areas of endometrioid neoplasia and negative staining with WT1 of use in excluding a serous neoplasm.International Journal of Gynecological Pathology 07/2014; 33(5). DOI:10.1097/PGP.0000000000000087 · 1.63 Impact Factor