Benign and malignant myoepitheliomas in salivary gland: cases report and immunohistochemical study

ABSTRACT

myoepithelioma (BME) and malignant myoepithelioma (MME) of the salivary gland are very rare and its biologic behavior has not been clarified fully. Although, cases reports for BME and MME were increased in recent, their diagnostic criteria were not completely established. We describe herein a case of BME of the parotid gland and a case of MME of the palatal minor gland, respectively. Histologically, multinodular growth pattern, infiltration to adjacent tissues, and hyalinized and myxoid matrix were observed in MME, that were different histologic features compared with BME. Strong immunoreactivities for the S-100 protein and vimentin were detected in the tumor cells of BME and MME. In specimen of MME, moderately expressed p53 and strongly expressed p63 were detected. However, in specimen of BME, p53 was negatively and p63 was weakly expressed, respectively. In conclusion, the expression patterns of p53 and p63 as well as histologic aggressiveness might be used to diagnose the MME.