Cytomorphologic features of low-grade endometrial stromal sarcoma.

Endometrial stromal sarcomas are uncommon tumors of the uterus, and the cytologic features have only been reported in a number of case reports that mostly discuss the features of higher grade undifferentiated sarcomas. This article discusses the cytologic features of a large series of low-grade endometrial stromal sarcomas (ESSs) sampled by a variety of methods. We reviewed our histologic files for all confirmed cases of low-grade ESS, and followed this by a computerized search for any corresponding cytologic specimens. We identified 12 Papanicolaou tests and 9 nongynecologic specimens. Most cases showed moderate to marked cellularity with a combination of single cells and stromal fragments. Blood vessels, interspersed between the clusters of stromal cells, were seen in 15 cases; 4 of these had supporting hyaline matrix. The cells were predominantly spindle shaped with scant to moderate cytoplasm, round to ovoid nuclei, and fine chromatin. Mitotic figures and nucleoli were rare. Most cases had a clean background.