Introduction/Background Gynecologic neuroendocrine carcinomas are rare, aggressive malignancies. The most common site is the cervix followed by the endometrium, ovary, vagina and vulva. Histological subtype and site of origin are major prognostic factors. We sought to characterize the cytomorphological features of these malignancies and compare them with histologic features.

Methodology Institutional databases were queried for gynecologic neuroendocrine carcinomas diagnosed between 2000 and 2021. All available cytological and surgical specimens were reviewed by 3 pathologists to evaluate the cytological and histopathological characteristics.

Results There were 22 patients (aged 29–74 years, median 48 years). Primary sites included cervix (n=13, small cell carcinoma), ovary (n=6; 3 small cell carcinoma of hypercalcemic type and 3 small cell neuroendocrine carcinoma) and endometrium (n=3; 2 small cell carcinoma and 1 large cell carcinoma). Results are summarized in table 1.Most cases showed round-to-oval nuclei with irregular contours. Among cervical specimens, common features were high cellularity, high nuclear: cytoplasmic ratio and moderate pleomorphism. Nuclear molding, naked nuclei, coarse chromatin and the absence of nucleoli were more prominent in cytologic specimens; mitoses, apoptosis, necrosis and the presence of rare nucleoli were more prominent in surgical specimens.In ovarian carcinomas, high nuclear:cytoplasmic ratio, naked nuclei, small to intermediate nucleoli and finely or coarsely granular chromatin were more prominent in cytologic specimens. Nuclear molding, mitoses and necrosis were more prominent in surgical specimens.For endometrial tumors, common cytological features included high cellularity, small clusters to single cells, high nuclear:cytoplasmic ratio, moderate pleomorphism, finely or coarsely granular chromatin, mitoses, and apoptosis.

Conclusion Given the rarity of neuroendocrine carcinomas arising in the gynecologic tract, a high index of suspicion is important when encountering neuroendocrine-like morphologic features in cytologic specimens in patients with suspected gynecologic malignancy. Careful attention to the morphology and confirmatory immunochemistry and molecular testing is important for accurate diagnosis.