Ovarian Teratomas Unveiled: Pathologists' Curiosity Reveals Intriguing Associations in the Enigmatic Realm

Mature and immature teratomas can coexist with other tumor types and they may undergo malignant change in any one of their elements. In the present study, we present our institutional experience of these rare associations with teratomas. This was a retrospective study over a period of 10 years (January 2014 to December 2023) on histopathologically diagnosed cases of ovarian teratomas. The clinicopathologic features of malignant transformation (MT), other associations, as well as co-existing tumors with ovarian teratomas were analyzed. There was a total of 602 (21%) ovarian teratomas out of all ovarian tumors (n=2858) reported during the study period. In all, 41/602(6.8%) cases were immature teratomas with the presence of gliomatosis peritonei in 7 cases. Mature cystic teratoma (MCT) cases also had gliomatosis peritonei (n=9) along with nodal gliomatosis in 3 cases. Neoplasms arising in teratomas (n=6) included carcinoid tumor (n=2), small cell neuroendocrine carcinoma (n=1), mucinous adenocarcinoma (n=2), and low-grade mucinous neoplasm of the appendix present within the teratoma (n=1). Of a total of 18 cases of struma ovarii, one case each of papillary thyroid carcinoma and follicular thyroid carcinoma was seen. Squamous cell carcinoma (n=4) was the commonest malignant transformation noted. Growing teratoma syndrome (n=4) and NMDA-associated encephalitis (n=3) associated with teratoma were also seen. Neoplasms/conditions co-existing with teratomas in the same ovary (n=9) included mucinous cystadenoma (n=1), serous cystadenofibroma (n=1), high-grade serous carcinoma (n=1), fibrothecoma (n=2), hydatid cyst (n=1), sclerosing stromal tumor (n=1), adult granulosa cell tumor (n=1), and metastatic signet ring cell carcinoma (n=1). Although the clinical course of MCT is typically indolent, pathologists should be aware of malignant transformation and other rare co-existing entities, highlighting the importance of adequate sampling of the tumors.