Case Study of a Parotid Gland Adenocarcinoma Dedifferentiated from Epithelial-Myoepithelial Carcinoma

الملخص EN

Dedifferentiation is defined as high-grade malignant tumor development out of a low-grade malignant tumor.

We present an adenocarcinoma tumor of the parotid gland that was dedifferentiated from a low-grade epithelial-myoepithelial carcinoma and was followed up for 3 years.

Our patient, a 46-year-old female, presented with a left parotid mass of 20-year duration.

Histopathologic results showed that there was only one area of typical epithelial-myoepithelial carcinoma, with foci of poorly differentiated adenocarcinoma (not otherwise specified; NOS) and clear cytoplasm in the parotid gland.

Immunohistochemical staining results showed SMA (+), P63 (+), CK8 (+), and S100 (+) on epithelial cells.

A review of the literature revealed 22 previously reported cases of dedifferentiated epithelial-myoepithelial carcinoma.

In these cases, the malignant tumors that dedifferentiated from epithelial-myoepithelial carcinoma were adenoid cystic carcinoma, actinic cell carcinoma, polymorphous low-grade adenocarcinoma, mucoepidermoid carcinoma, and intraductal carcinoma.

In our case, the malignant tumor that dedifferentiated from the epithelial-myoepithelial carcinoma was a poorly differentiated adenocarcinoma.

Histopathological results showed that metastases were not seen in the neck-dissection material.

As a result, our case will make a contribution to the literature in terms of prognosis, because there are very few reported cases of dedifferentiated adenocarcinoma development arising from epithelial-myoepithelial carcinoma.