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Case Reports in Otolaryngology
Volume 2014 (2014), Article ID 629054, 3 pages
Case Report

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

1Department of Otolaryngology, Bağcılar Education and Research Hospital, Istanbul, Turkey
2Department of Pathology, Bağcılar Education and Research Hospital, Istanbul, Turkey

Received 3 July 2014; Revised 21 August 2014; Accepted 27 August 2014; Published 9 September 2014

Academic Editor: Kai-Ping Chang

Copyright © 2014 Salih Aydın et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.