Morphological and Immunohistochemical Support for the Origin of the Carcinoid Component in Strumal Carcinoids: A Case Report and Literature Review.

Strumal carcinoid tumors of the ovary are rare neoplasms composed of an intimate mixture of thyroid and carcinoid tissues. Although various theories regarding their histogenesis have been proposed, evidence confirming the origin of the carcinoid component has been lacking. We report a case of a 40-year-old female with an ovarian strumal carcinoid arising in the background of a mature cystic teratoma. Morphological and immunohistochemical findings support the hypothesis that the carcinoid component originates from the thyroid follicular epithelium, undergoing neuroendocrine differentiation. A single-cell growth pattern was also identified, expanding the known histological spectrum of strumal carcinoids. Our case provides additional immunohistochemical support for the histogenetic origin of strumal carcinoids, offering new insights into their pathogenesis. Recognizing these distinct patterns of staining and unusual morphology is critical for accurate diagnosis and differentiation from metastatic disease.