ENDOMETRIOID-LIKE VARIANT OF OVARIAN YOLK-SAC TUMOR WITH FOCI OF CARCINOID - AN ULTRASTRUCTURAL-STUDY

The endometrioid-like variant of ovarian yolk sac tumor is a rare neoplasm composed partially or completely of glandular tissue resembling endometrioid carcinoma, but identifiable histologically and immunohistochemically as an extraembryonic endodermally differentiated germ cell tumor. Only nine examples of this neoplasm have been published previously, and none was studied by electron microscopy. One of these rare neoplasms, the first documented to have foci of carcinoid, has recently been observed and studied ultrastructurally. Electron microscopic observations showed that the main component of the neoplasm had glandular epithelial cells with nuclear and cytoplasmic features difficult to distinguish from the cells of Mullerian endometrioid and endometrial adenocarcinoma, but a minor component of mucinous adenocarcinoma was confirmed as intestinal by the epithelial cells having characteristic microvilli with filamentous cores and rootlets. In addition, neuroendocrine cells present in the glands and in nests were readily identified ultrastructurally by their dense-core granules. Electron microscopy may be useful in supplementing light microscopic and immunohistochemical examination of this variant of yolk sac tumor.