Exfoliative Cytology of Neuroendocrine Small Cell Carcinoma of the Endometrium

Abstract

In the female genital tract, neuroendocrine small cell carcinoma can occur in the endometrium as well as the cervix, ovary and vagina. This tumor has a high propensity for systemic spread and a poor prognosis. Small cell carcinoma of the endometrium is cytologically identical to its counterparts in the lung and other sites. Its characteristic appearance in a cervicovaginal smear should raise concern about small cell carcinoma. Other tumors of the uterus should be considered in the differential diagnosis, including adenocarcinoma with neuroendocrine features, small cell nonkeratinizing squamous cell carcinoma, endometrial stromal sarcoma, rhabdomyosarcoma, primitive neuroectodermal tumor, non-Hodgkin's lymphoma and metastatic breast carcinoma. Case 1 was a 59-year-old, white female, and case 2 was a 47-year-old, white female. Both patients presented with vaginal bleeding. The Papanicolaou smears in both cases had similar, characteristic exfoliative cytology. The tumor cells were small and either single or arranged in groups and files. They had barely visible cytoplasm, darkly staining nuclei with finely stippled chromatin, and inconspicuous nucleoli. The characteristic molding of the nuclei was also present. Immuno-histochemical staining for neuron-specific enolase and synaptophysin was positive in tissue sections. Pancytokeratin, vimentin, muscle-specific actin, desmin, alpha-fetoprotein, S-100, glial fibrillary acid protein, common leukocyte antigen and chromogranin were negative. When a uterine small cell carcinoma is suspected in a cervicovaginal smear, the similarity of cervical and endometrial small cell carcinoma requires a differential curettage and immunohistochemical demonstration of neuroendocrine differentiation in order to arrive at the final diagnosis.