Aspiration biopsy cytology of metastatic endometrial stromal sarcoma and extragenital mixed mesodermal tumor.

Aspiration biopsy from metastatic tumors in two cases of endometrial stromal sarcoma and one case of endometrial adenosarcoma revealed malignant endometrial stromal cells with ill-defined cytoplasm and round or oval hyperchromatic nuclei showing irregular chromatin clumping and conspicuous nucleoli. They were seen mainly in clusters. Aspirate from a metastatic tumor of a mixed mesodermal tumor arising from the omentum showed similar malignant endometrial stroma cells, irregular tight clusters of malignant glandular cells having scanty but well-defined cytoplasm and vesicular nuclei with conspicuous nucleoli, and fragments of atypical smooth muscle tissue. The diagnostic malignant endometrial stromal cells in those reported cases did not display any distinctive cellular features permitting their cytologic identification. They were difficult to differentiate from those of other types of sarcoma. In a clinical setting, with a known primary endometrial stromal sarcoma or mixed mesodermal tumor, however, a cytodiagnosis of its metastases may be suggested when malignant endometrial stromal-cell-like cells are seen in aspirated material, oviating an open-tissue biopsy.