High-grade carcinoma component in epithelial-myoepithelial carcinoma of salivary glands clinicopathological, immunohistochemical and flow-cytometric study of three cases

Three cases of epithelial-myoepithelial carcinoma (EMC) with coexisting are as of high grade carcinoma are reported, In two of the cases there was a pr evious recurrence, and in all three patients there had been a sudden increa se in size before final surgery. The typical ductal and myoepithelial compo nents of EMC showed the usual biphasic pattern and the expected immunopheno types, with expression of wide spectrum cytokeratins, Cam 5.2 and EMA in th e ductal part, and muscle-specific actin, smooth muscle actin, S-100 protei n, vimentin and cytokeratins in the myoepithelial component. These areas al so had a low mitotic count and low proliferation rate as measured by immuno histochemistry and by flow cytometry. Conversely, areas of high-grade tumou r had the features of a large cell carcinoma, with focal mucin secretion in two cases. This high-grade component showed an epithelial immunophenotype in two cases, and was negative for all tested markers in the third one. The mitotic counts and the proliferation rates were much higher in these anapl astic areas. One of the patients died 3 months after treatment; another dev eloped lymph node metastases 1 year later and was alive after 6 years of fo llow-up. The third patient was alive without evidence of disease 7 months a fter wide surgical resection of the tumour. The possibility of anaplastic t ransformation in EMC makes thorough sampling mandatory in this type of neop lasm.