Cytological features of epithelioid mesenchymal neoplasms: a study of 21 cases

Epithelioid mesenchymal neoplasms (EMNs) are rare tumors that share cytological, histological, and immunohistochemical features with epithelial tumors. It is important to distinguish EMNs from epithelial tumors in cytology specimens due to their different clinical management and prognosis. The cytomorphological features of histologically confirmed EMN were reviewed. Twenty-one cytological specimens of EMN were evaluated and characterized by polygonal cells with moderate to abundant dense cytoplasm, prominent nucleoli, and pleomorphism. Additional findings included the presence of a distinct population of spindle cells, hemosiderin-containing cells, multinucleated cells, and granuloma-like structures in selected cases. Cytokeratin immunoreactivity was seen in two cases and was negative in one case. This study shows that the cytological features of EMNs and epithelial tumors overlap; nonetheless, some features are more helpful in suggesting EMN. A panel of immunocytochemical studies must include specific mesenchymal markers to avoid a misdiagnosis of carcinoma in cases of cytokeratin-positive EMN.