Cytologic features of malignant ovarian monodermal teratoma with an ependymal component in peritoneal washings

A case of malignant neuroectodermal tumor of the ovary (monodermal teratoma) with a predominant ependymal component in the peritoneal washings of a 27-year-old woman obtained on second-look laparotomy is presented and discussed. The smear and cell block preparations showed sheets and clusters of cells containing oval nuclei with finely granular chromatin and small nucleoli. The cell nuclear/cytoplasmic ratio was within normal limits, and minimal cytologic atypia was observed. The clusters were rimmed by columnar-oriented cells lined by cilia. This is the first reported case of this rare ovarian neoplasm present on fluid cytology. Its bland cytologic appearance could be confused with endosalpingiosis.