Cytomorphology of small-cell (neuroendocrine) carcinoma on ThinPrep cytology as compared to conventional smears.

Small-cell (neuroendocrine) carcinoma of the female genital tract is an uncommon, aggressive neoplasm that occurs most commonly in the cervix and rarely in the vagina. Although the cytologic findings have been reported on conventional smears, the cytologic diagnosis of primary vaginal small-cell carcinoma on ThinPrep material has not been previously reported. We present a case of a 46-yr-old woman who underwent cervical/vaginal biopsies as a result of abnormal cells seen on the ThinPrep Pap Test. Small to medium-sized cells with scant cytoplasm were present singly and in loose, cohesive clusters. Nuclear molding was noted in a few cellular groups. The differential diagnosis included a high-grade squamous intraepithelial lesion, small-cell (neuroendocrine) carcinoma, endometrial adenocarcinoma, and lymphoma. Subsequent tissue biopsies with immunohistochemical staining confirmed a diagnosis of small-cell carcinoma of the vagina. The cytologic features of small-cell (neuroendocrine) carcinoma on slides prepared by the ThinPrep Pap Test are discussed and compared to those on conventional cervicovaginal smears.