EPITHELIAL-MYOEPITHELIAL CARCINOMA OF SALIVARY-GLANDS - A CLINICOPATHOLOGICAL, DNA FLOW CYTOMETRIC, AND IMMUNOHISTOCHEMICAL STUDY OF KI-67 AND HER-2 NEU ONCOGENE/

Thirty-one salivary gland epithelial-myoepithelial carcinomas from 26 patients were studied by DNA flow cytometry, and immunostaining for Ki -67 and HER-2/neu oncogene product. The results were correlated with c linicopathologic factors and patient outcome. The tumor most commonly involved the parotid gland, and mainly affected patients in their 6th to 8th decades. The clinical course was characterized by a high incide nce of local recurrence (50%) and not infrequent distant metastasis (2 5%). None of the patients in this cohort died of disease. DNA content analysis revealed 21 neoplasms with DNA diploidy and 5 tumors with DNA aneuploidy; all aneuploid cases were near-diploid (hyperdiploidy) and showed low proliferative activity. All aneuploid and 60% of the diplo id neoplasms developed recurrences and/or metastases. Immunohistochemi cal analysis of Ki-67 proliferation markers also showed low overall gr owth fractions. Interestingly, Ki-67 immunoreactivity was largely rest ricted to myoepithelial cells, suggesting a central role for this cell in the development of these tumors. HER-2/neu oncogene analysis faile d to demonstrate overexpression in any of the tumors examined. This st udy indicates that epithelial-myoepithelial carcinoma is a low grade m alignant neoplasm with a high propensity for recurrence. HER-2/neu onc ogene and Ki-67 offer no additional advantages over current factors in the biologic evaluation of these neoplasms. DNA aneuploidy may allow for the identification of a subset of tumors that is more prone to rec urrence and metastasis, but further studies with extended followup are needed.