Clinicopathologic And Immunohistochemical Study Of Malignant Myoepithelioma Of Salivary Gland

Objective : Malignant myoepithelioma (MME) of salivary gland , also known as myoepithelial carcinoma, is rare and its biologic behavior has not been clarified entirely . Immunohistochemical study was applied to explore clinicopathologic characteristic and behavior and expression of c-erbB-2 oncogene , proliferating cell nuclear antigen(PCNA) and mutant p53 protein in malignant myoepithelioma(MME) of salivary glands .Methods : 30 cases of malignant myoepithelioma and 20 cases benign myoepithelioma(BME) were analyzed. Myoepithelioma has three cellual types : epithlioid , spindie and plasmacytoid cells . MME was comprised of tow cell types or a combination of more than two cell populations . The thirty patients with MME ranged in age from 24 to 72 years old (mean , 52.9 years). We study 18 men and 12 women patients with MME , sex distribution was men more than women . All the tissue sections were fixed in 10% formalin and processed using routine histologic techniques . The specimens were stained respectively by c-erB-2 , p53 and PCNA ,then immunohistochemically analyzed .Results : The tumor arise most frequently within the parotid glands , the submandibular salivary gland and can arise in minor salivary glands . Sex distribution was men more than women , the median age was 52.9 years . It was shown that MMEs were comprised of one cell type or a combination of two cell populations;these include , epithlioid , spindle and plasmacytoid cells . Immunohistochemically , 4 BMEs and 17 MMEs were overexpression of c-erbB-2 oncoprotein . The salivary ductal epithelial cells near tumors were overexpression of c-erbB-2 oncoprotein in 8 cases . The proliferation index (PI) proliferating cell nuclear antigen(PCNA) was higher in MMEs than in BMMs (p<0.0\) . The p53 protein was positive in 24 MMEs , wheras all BMEs were negative .Conclusions : The c-erbB-2 oncoprotein may be an initial oncogene during histogensis . PCNA and the mutation of p53 protein may play an important role in malignant myoepithelioma.