A Case of Metastasizing Pleomorphic Adenoma of the Parotid Gland Diagnosed from a Renal Metastasis

Abstract

We report a case of metastasizing pleomorphic adenoma of the parotid gland that was diagnosed from a renal metastasis.

The patient was a 63-year-old man who was referred to our Department of Urology with a right kidney tumor detected on abdominal CT. Right nephrectomy was performed and histopathologic examination of the resected tumor revealed features consistent with pleomorphic adenoma. Careful examination revealed a right parotid tumor, and the patient was referred to our department. The patient had first noticed the right parotid tumor 10 years ago; it had been biopsied then and declared as being non-malignant by neighborhood doctor. The right parotid tumor was excised and the histopathological findings resembled those of the kidney tumor. The patient was diagnosed as having metastasizing pleomorphic adenoma of the parotid gland. In case of metastasizing parotid adenoma, usually, the metastasizing pleomorphic adenoma recurs locally after parotid tumor surgery, and metastasis is confirmed subsequently. Our case was an extremely rare case, in that the patient presented with a renal metastasis even in the absence of a history of surgery. We review some cases of metastasizing pleomorphic adenoma reported in the literature.