Mucoepidermoid carcinoma

Mucoepidermoid carcinoma is a malignant tumor composed of a variable admixture of epidermoid and mucous cells arising from the ductal epithelium of the salivary glands. This is the most common malignant salivary gland tumor (35%). Just over half occurs in the major salivary glands, most commonly the parotid gland; the rest are found in the minor glands, with the palate being the most frequent location. The aggressiveness of the lesion varies with the histologic grade. A wide age range exists, with the highest prevalence in the fifth decades of life. A slight predilection for female exists. The low grade variety rarely metastasizes. Clinically, this nodule not unlike a benign mixed tumor. It is usually only 1-4 cm in diameter. The prognosis is good. The 5 year survival rate is greater than 95%. In contrast to low grade mucoepidermoid carcinomas, high-grade tumors often cause pain and paralysis, have ill defined margins and are relatively immobile. Metastasis by blood and lymph are common, with recurrence in half the patients after excision. The prognosis is poor and varies with the histologic grade, the 5 –year survival rate may be as low as 25%.