Salivary Gland Cancer Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Cellular Classification of Salivary Gland Cancer
In a review of its case files, the AFIP found adenoid cystic carcinoma to be the fifth most common malignant epithelial tumor of the salivary glands after mucoepidermoid carcinomas; adenocarcinomas, NOS; acinic cell carcinomas; and PLGA. Other series, however, report adenoid cystic carcinoma to be the second most common malignant tumor with an incidence or relative frequency of approximately 20%. In the AFIP data, this neoplasm constitutes approximately 7.5% of all epithelial malignancies and 4% of all benign and malignant epithelial salivary gland tumors. The peak incidence for this tumor is reported to be in the fourth through sixth decades of life.
This neoplasm typically develops as a slow growing swelling in the preauricular or submandibular region. Pain and facial paralysis develop frequently during the course of the disease and are likely related to the associated high incidence of nerve invasion. (Refer to the PDQ summary on Pain for more information.) Regardless of histologic grade, adenoid cystic carcinomas, with their unusually slow biologic growth, tend to have a protracted course and ultimately a poor outcome, with a 10-year survival reported to be less than 50% for all grades.[1,27] These carcinomas typically show frequent recurrences and late distant metastases.[1,28] Clinical stage may be a better prognostic indicator than histologic grade.[28,29] In a retrospective review of 92 cases, a tumor size larger than 4 cm was associated with an unfavorable clinical course in all cases.
Acinic cell carcinoma
Acinic cell carcinoma, also known as acinic cell adenocarcinoma, is a malignant epithelial neoplasm in which the neoplastic cells express acinar differentiation. By conventional use, the term acinic cell carcinoma is defined by cytologic differentiation towards serous acinar cells, as opposed to mucous acinar cells, whose characteristic feature is cytoplasmic periodic acid-Schiff (PAS)-positive zymogen-type secretory granules. In AFIP data of salivary gland neoplasms, acinic cell carcinoma is the third most common salivary gland epithelial neoplasm after mucoepidermoid carcinoma and adenocarcinoma, NOS. In these data, acinic cell carcinoma comprised 17% of primary malignant salivary gland tumors or about 6% of all salivary gland neoplasms; more than 80% occur in the parotid gland; women were affected more than men; and the mean age was 44 years. Other studies have reported a relative frequency of acinic cell carcinoma from 0% to 19% of malignant salivary gland neoplasms.