[A case of metastatic renal tumor originating from a malignant mixed tumor of the submandibular gland].

A rare case of metastatic renal tumor originating from a malignant mixed tumor of the submandibular gland is reported. The patient was a 45-year-old woman with hard masses palpated in the right upper arm and the right upper gluteal region. She had a history of surgical resection of a right submandibular tumor followed by radiotherapy in 1977. Biopsy findings of the gluteal mass suggested a malignant clear cell tumor. A chest X-ray, excretory urogram, CT scan, MRI and renal angiogram were highly suggestive of a right renal cell carcinoma with metastases to the right lung (S1 & S10), the left 4th and 5th ribs, the right upper arm muscle and the right upper gluteal muscle. Right nephrectomy and resection of the right upper arm and right upper gluteal tumors were performed. Microscopic examination showed that all tumors were malignant mixed tumors. When compared to the previous surgical specimen, the tumors were believed to be identical. The tumors of the lung and ribs subsequently resected were malignant mixed tumors. The patient is well with no objective or subjective evidence of recurrent neoplastic disease 7 months post-operatively. To our knowledge only one report of metastatic renal tumor originating from a malignant mixed tumor of the salivary gland has been published in Japan. But metastatic renal tumor originating from the same tumor of the submandibular gland has not been reported previously in Japan.