Immunohistochemical study on an epithelial-myoepithelial intercalated duct carcinoma transplanted to the nude mouse.

Parotid gland carcinomas are rare. Among them, the epithelial-myoepithelial carcinoma (EMC) is extremely rarely diagnosed. This case report was based on a female with a history of 17 years of recurrent EMC of the parotid and evidence of distant metastasis over a period of 2 years. During debulking procedures of her extensive facial tumour, small tumour samples were transplanted to nude mice. The tumours grew well on the mice and were characterized morphologically and immunohistochemically after explantation. Cellularity per mm(2) ranged between 3,470 and 7,410. The tumours were characterized by the typical bipolar pattern of tumour cells and broad stromal septae. All but one of 7 transplanted tumours were positive for pan-cytokeratin marker KL-1. The proliferation index in terms of MIB-1-stained nuclei increased from 2% to 20% and was correlated positively to the expression of EGFR. IGF-1R-, VEGF- and FLK1-stained cells were found in all cases. The increase in EGFR- and MIB-1-positive cells correlated with the clinical course of the patient, who showed shorter periods of tumour recurrence prior to her death. These findings in EMC transplanted to the nude mouse demonstrate the feasibility of growing EMC in vivo.