acinic cell carcinoma of the parotid gland with four morphological features

acinic cell carcinoma arising in salivary glands is a rare tumor, accounting for 2% to 5% of the primary neoplasms of the parotid gland. when these tumors are well-differentiated, the neoplasia has innocuous aspect, due to the similarity to normal parotid tissue. this makes the diagnosis difficult. initially the malignancy of this tumor was uncertain; however, recent studies have declared it as malignant. the female / male ratio is 3:2. the nodule usually presents as solitary and well defined shape. several authors have used different terms to describe histomorphological patterns of these tumors. four descriptive categories (solid, microcystic, papillary-cystic and follicular) are useful for pathologists. here we report a case of a 49 yr old man with a left parotid nodule of 5 cm. parotidectomy was performed at the hospital universitario miguel servet, in zaragoza (spain). the microscopy showed a tumor with acinic semblance, having the four morphologic patterns previously described. the morphological and immunohistochemical study was consistent with the diagnosis of acinic cell carcinoma.