Epithelial –myoepithelial carcinoma ex-pleomorphic adenoma of the parotid gland: report of a rare case with immunohistochemical and genetic analyses

We examined one additional case of EMCa ex-PA, immunohistochemically and genetically. The patient was an 83-year-old female , who suffered from swelling of the right parotid region. Histologically, the tumor contained a hyalinized nodule, which displayed elastosis. The main tumor exhibited a bi-layered structure, involving inner ductal cells and clear outer myoepithelial cells. Immunostaining indicated that the inner cel ls were positive for epithelial membrane antigen, whereas the outer cells were positive for p40. On the genetic level, the carcinoma harbored noHRAS gene mutations, whereas fluorescence in situ hybridization (FISH) of thePleomorphic Adenoma Gene1 showed splitting signals in the carcinomatous component. We diagnosed this case as EMCa ex-PA. It is necessary to differentiate EMCa ex-PA from myoepithelial carcinoma and clear cell carcinoma, and FISH is useful for such purposes.
Source: Medical Molecular Morphology - Category: Molecular Biology Source Type: research