[Myoepithelial carcinoma (malignant myoepithelioma) of the salivary glands. A case report]

[Rare malignant tumor of the parotid gland. Myoepithelial carcinoma]

A parotid mass in a 62-year-old woman presented intraoperatively as a highly malignant tumor with facial nerve infiltration. Classification by means of rapid section histology was not possible. Immunohistochemical studies were necessary to diagnose this rare case of myoepithelial carcinoma of the parotid gland. We performed a total parotidectomy including partial nerve resection and neck dissection on the tumor side. The patient was referred to radiotherapy postoperatively.

[Cystic myoepithelioma. A rare differential diagnosis of a cystic lesion of the parotid gland]

By sonography, we found a sharply demarcated tumor with cystic areas in the parotid gland of a 41 year old male, indicating Warthin's tumor. Subtotal parotidectomy was performed. Microscopy showed an encapsulated tumor with myoepithelial cells and, in particular, central pseudocysts. Immunohistochemically, the tumor cells expressed cytokeratin 5/6 and S-100 protein as well as smooth muscle-actin. These features led to the diagnosis of a cystic myoepithelioma. Histopathologically, several different lesions of the salivary glands should be considered in the differential diagnosis of myoepithelioma, especially of this hitherto unique case in the parotid gland. The differential diagnoses are reviewed and discussed. Treatment is by surgical resection. Because of the tendency of myoepitheliomas to recur and to malignant transformation, tumor-free margins are recommended.