Myoepitheliales Karzinom der Glandula parotis: Ein seltener Tumor mit diagnostischer Herausforderung

We report on the occurrence of a myoepithelial carcinoma (MC) of the parotid gland in a 58-year-old female patient, 6 years after total parotidectomy of a locoregional myoepithelioma. Due to the rapid growth in the former resection area, panendoscopy and tumor extirpation of the right parotid region were performed. From a histomorphological and cytomorphological point of view, a hyalinized clear cell carcinoma of the salivary gland was originally diagnosed. After further immunohistochemical investigations and preparation of deeper section levels the morphological picture and immunohistochemical expression pattern corresponded to a myoepithelial carcinoma of the salivary gland, with focal lateral excision margins. Based on the radiological impression of suspicious lymph nodes during the staging examinations and the perineural invasion in the histological findings, modified radical neck dissection of the ipsilateral levels I-V was performed. All lymph nodes were histologically negative. An adjuvant radiotherapy was then initiated. The patient is tumor-free 7 months after surgery and after completing the adjuvant radiation treatment. Clinical assessment of the facial nerve showed House-Brackmann grade 5 facial palsy. The aim of this case report is to describe the difficulties in the diagnostics and treatment of this rare entity.