[Malignant mixed tumor].

The term "malignant mixed tumor" is usually synonymous with "carcinoma in pleomorphic adenoma," a secondary carcinoma developing in pre-existing pleomorphic adenoma. However, it sometimes indicates a group of tumors consisting of carcinoma in pleomorphic adenoma, carcinosarcoma (true malignant mixed tumor) and metastasizing benign mixed tumor, the latter 2 being the most infrequent. According to the data of the Japanese committee on TNM classification for salivary gland carcinomas, carcinoma in pleomorphic adenoma accounted for about 10% of all salivary gland carcinomas, both in the parotid and submandibular glands. The main type of carcinomas arising in pleomorphic adenoma were undifferentiated carcinoma, adenocarcinoma and squamous cell carcinoma. Crude 5- and 10-year survival rates were 54.7% and 42.7%, respectively. Invasive carcinomas and carcinomas of high grade malignancy carried worse prognoses. The treatment of choice for carcinoma in pleomorphic adenoma has consisted of en-bloc excision with wide margin. Invasive growth, facial nerve involvement, lymph node metastasis or high-grade malignant tumor are grounds for postoperative radiation therapy. The role of chemotherapy has not yet been well established.