Simultaneous occurrence of an intraductal adenocarcinoma and an invasive myoepithelial carcinoma in a recurrent pleomorphic adenoma of the parotid gland - a case report.

Introduction Carcinomas ex pleomorphic adenomas are, as the name implies, carcinomas which develop in pleomorphic adenomas. During the carcinogenesis, they develop from an intraductal early stage to an extracapsular-invasive growth. Excluded from this are myoepithelial carcinomas, which develop from myoepithelial cells and for which an intraductal stage has not been described.

Case report We present a 72-year-old patient with a bifocal carcinoma ex pleomorphic adenoma. The patient was admitted with an enlarging mass of the parotid gland. Around 30 years prior a pleomorphic adenoma was resected from the same gland.

Clinical examination showed a firm, defined mass measuring 2x3 cm. Ultrasound showed a hypoechoic, well-circumscribed, rounded lesion of 2x3x3.5cm.

During lateral parotidectomy it was seen that the facial nerve was directly adherent to the mass. The histopathological report showed a finding, which according to our literature research was described for the first time. Within a typical recurrence of a pre-operated pleomorphic adenoma it showed an intraductal carcinoma ex pleomorphic adenoma right next to an extracapsular-invasive, highly differentiated myoepithelial carcinoma ex pleomorphic adenoma.

Discussion Due to the pathogenesis of carcinomas ex pleomorphic adenomas, we hypothesize the first described case of a simultaneous, separated development of two carcinomas from two different recurrences of pleomorphic adenoma.

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Publication History

Article published online:
13 May 2021