Updated Morphological and Immunohistochemical Profile of Neuroendocrine Tumors Developed in Ovarian Teratomas: A Large Series of a Rare and Heterogeneous Disease

Abstract

Abstract Introduction Ovarian carcinoid tumors are rare, often arising within a mature teratoma of the ovary. No recent reevaluation of the immunophenotype of these tumors with the new markers available in the field of neuroendocrine neoplasms has been performed. The objectives were to describe the morphological and immunohistochemical characteristics of neuroendocrine tumors (NETs) arising from ovarian teratomas, to correlate them with the type of teratomatous epithelial components present and to evaluate their proliferative capacities using the WHO recommendations for gastroenteropancreatic NETs. Materials and Methods This is a bi-centric retrospective study using a panel of differentiation markers (chromogranin-A, Synaptophysin, CDX2, SATB2, TTF1, PAX8, Islet-1, Serotonin and Calcitonin) and Ki-67 proliferation. Results The 34 NETs studied were unilateral and presented four distinct immunophenotypic profiles: 8 NETs expressed serotonin and CDX2 (small intestine profile), 12 SATB2 (colorectal profile), one TTF1 (thoracic profile) and 4 “null” cases expressed none of the above markers. Ki-67 index ranged from 0 to 19.82% (median: 1.51%). 28 cases were of grade 1 (84.8%), 5 grade of 2 (15.2%). They were associated with squamous (n = 26), respiratory (n = 23), thyroid (n = 10) and gastrointestinal (n = 5) components. Discussion and Conclusion The main type of NET is intestinal (large or small intestine) phenotype, but rarely accompanied with the corresponding digestive tissue in the surrounding teratoma. This suggests that the cell of origin might be a neuroendocrine precursor present in the teratoma, and confirms that primary NETs arising in ovarian teratoma should not be classified or named according to the type of the surrounding teratoma tissue.