Fine-needle aspiration cytology of carcinosarcoma of the parotid gland: cytohistological and immunohistochemical findings.

Carcinosarcoma or true malignant mixed tumor of salivary glands is a very rare neoplasm which shows malignant features of the epithelial and mesenchymal components. We hereby present cytological, pathological, and immunohistochemical findings of one such case, first examined by fine-needle aspiration cytology. The aspirate was cell-rich and consisted of large cell clusters which at low magnification showed an arrangement reminiscent of a jigsaw puzzle. An amorphous substance was observed in the middle of some of these clusters. There were also numerous dissociated cells which often displayed marked atypia. Histology showed a tumor with malignant epithelial and mesenchymal components. The carcinomatous areas consisted of cells arranged in solid nests or glandular structures. The sarcomatous areas showed osteosarcoma, low-grade chondrosarcoma, and undifferentiated components. On immunohistochemistry, the tumor coexpressed epithelial and mesenchymal markers. Cytokeratin, keratin, and epithelial membrane antigen were mainly localized to the carcinomatous portion, whereas vimentin and neuron-specific enolase were restricted to the sarcomatous areas. S-100 protein was positive in both. Our findings support previous views that this tumor may be related to pleomorphic adenoma.