[A case of parotid pleomorphic adenoma metastasis to multiple organs]

In January 2011, a 64-year-old woman who had undergone tumor resection for pleomorphic adenoma of the left parotid gland four times since her first operation in 1996 visited an orthopedist in our hospital complaining of pain in her right lower limb. Computed tomography (CT) of the whole body showed multiple tumors on the left parotid gland, right kidney, the sacrum, and both lungs. Biopsy of the sacral region and right nephrectomy were performed based on a clinical diagnosis of sacral and pulmonary metastases from renal cell carcinoma, and palliative radiation therapy was immediately begun on the sacral region. Given the definitive pathological diagnosis of metastasis of pleomorphic adenoma of the parotid gland, the recurrent tumor of the left parotid gland and the surrounding lymph nodes were first removed. Postoperative findings demonstrated that the pleomorphic adenoma had metastasized to the lymph nodes. The lung tumors were resected subsequently, and postoperative findings led to the diagnosis of pleomorphic adenoma. Metastasis of pleomorphic adenoma is known to be extremely rare, and to our knowledge this case of metastasis to a kidney is the first reported in Japan.