Large carcinoma ex pleomorphic adenoma of the parotid gland: a case report and review of literature.

Pleomorphic adenoma (PA) is one of the most common benign tumors of the parotid gland. PA usually grows slowly and is painless. Surgery is necessary for treating PA. Facial palsy, salivary fistula, and Frey syndrome have been reported as complications of tumor resection. PA can transform into a carcinoma ex pleomorphic adenoma (CXPA) over time and as it enlarges. This report describes a case of a large CXPA that transformed from a PA that had developed over 17 years and caused withdrawal from social contact because fear of surgery made the patient refuse treatment. The tumor gradually enlarged without any pain for a decade, but rapid growth and bleeding began a year before admission. Postoperative facial function and local control of the tumor were excellent, but the patient required adjuvant chemotherapy for lung and mediastinum lymph node metastasis leading to dyspnea from tracheal stenosis. This case indicates the importance of adequate explanation and advice when choosing therapy for PA, especially given the risk of a PA transforming to a CXPA.