Endometrial stromal sarcoma with clonal chromosomal aberrations and mixed phenotype

We report a case of moderate-grade endometrial stromal sarcoma with the following chromosomal complement based on the evaluation of 43 metaphases: 47,XX,der(3)t(3;6)(q29;p21.1),der(6) t(3;6)(q21;q27), + 19. Immunohistochemically, the paraffin-embedded tumor tissue displayed positive vimentin reactivity and lack of cytokeratin expression, indicating a mesenchymal origin. Interestingly, the cultivated tumor cells revealed a co-expression of vimentin and different subtypes of cytokeratin. Therefore, the cytogenetically monoclonal tumor cells which showed co-expression of epithelial and mesenchymal phenotypes suggest that the endometrial stromal sarcoma can be interpreted as a monophasic variant of the malignant mixed Müllerian tumor.