Primitive neuroectodermal tumor of the uterus. A case report.

BACKGROUND: Primitive neuroectodermal tumor (PNET) is a rare tumor derived from fetal neuroectodermal cells. These tumors occur in the central nervous system and in peripheral locations. Histologic diagnosis is the standard since most of these tumors are detected at an advanced stage. CASE: A 17-year-old female presented with persistent vaginal bleeding. Physical examination revealed a 4-cm, hard, barrel-shaped cervix. A cervicovaginal smear was obtained. The specimen was hypercellular, with small to medium-sized, round, malignant cells. A diagnosis of PNET was made from the histologic sections of the surgical specimen. CONCLUSION: When numerous small round cells in a diffuse pattern are seen on a Pap smear, the differential diagnosis is long and difficult. However, with careful evaluation of the cytologic features, a few reasonable differential diagnoses can be reached. Furthermore, with liquid-based Pap smears, material is available for immunohistochemical staining to narrow the range even more. Using all resources, including a good clinical history, a cytopathologist can give the clinician an early diagnosis for intervention and treatment.