Acinic cell carcinoma is the fourth most common malignant salivary gland tumor, following mucoepidermoid carcinoma, adenoid cystic carcinoma, and carcinoma ex pleomorphic adenoma; it occurs more frequently than primary squamous cell carcinoma.
Acinic cell carcinoma is a rare, low-grade malignant salivary gland neoplasm. These are malignant tumors of the salivary glands that are dervied from the salivary gland epithelium and characteristically forms glandular acini. It is notable for an unpredictable clinical course with both local recurrence and distant metastase. Approximately, 20% of patients experience local recurrence and 10% distant metastasis, often many years after initial presentation. Pain or tenderness may be present in up to 1/3 of patients. The disease presents as a slow growing mass, sometimes associated with pain or tenderness. A history of exposure to radiation should be sought in patients with salivary gland neoplasms of the larynx or trachea.
Women are affected more often than men, and the age at occurrence is earlier than in other salivary gland cancers. Although acinic cell lesions usually are seen in the parotid gland, they occasionally occur in the submandibular gland. They are low grade, only infrequently invade the facial nerve, and are late to metastasize. When they do metastasize, however, it is usually to the lungs, and under these circumstances, death usually follows. Because of their slow growth, survival data are good when generous surgical excision is performed.
Although acinic cell carcinomas rarely metastasize, they have a high tendency to recur locally if they are incompletely excised. Facial nerve weakness that is associated with a parotid or submandibular tumor is an ominous finding. Even in huge tumors of the parotid gland that are benign, the facial nerve usually is not affected. Essentially, any compromise in nerve function greatly heightens concern for malignancy. Overall, malignant parotid gland tumors are associated with facial nerve paralysis in 10% to 20% of patients. The survival rates for malignant salivary gland tumors depend on the cell type and the stage of the cancer. The stage of the cancer depends on its size and whether or not it has spread to other parts of the body. Some patients may benefit from adjuvant radiation therapy.
