Epithelial-myoepithelial carcinoma accounts for approximately 0.5-1% of all salivary gland neoplasms and favors women by a ratio of 2:1 [446, 466]. The vast majority arise in the major as opposed to the minor salivary glands. The parotid gland is the site of approximately 75% with an additional 10-12% arising in the submandibu-lar gland. Origin from minor salivary glands primarily occurs in the palate [505, 561]. EMC has also arisen in extraoral mucoserous glands in the nasopharynx, larynx, and bronchi . Interestingly a histologically identical tumor occurs in the breast where it is still known as an adenomyoepithelioma [129, 132, 256, 417, 491].
Epithelial-myoepithelial carcinoma is essentially a tumor of older adults (mean age 60 years) although rare cases have been reported in the pediatric age group and we have seen one unreported case in a 6^-year-old child [124, 159]. Patients usually present with an asymptomatic mass. Much less frequently signs and symptoms of a malignant neoplasm, such as facial paralysis and pain, are present. In some instances a mass has been present for several years prior to the patient seeking medical treatment .
phism and increased mitotic activity. Histologic evidence of malignancy is reflected in areas showing an infiltrative growth pattern and perineural invasion. Prominent collars of PAS-positive diastase-resistant basement membrane material surrounds the duct-like structures which in turn form nests of tumor separated by fibrous bands of connective tissue. This results in a multilobulated appearance (Fig. 3.16). In the cribriform growth pattern two cell populations are still discernable and, while the cribriform pattern can mimic an adenoid cystic carcinoma, no hyaline material is present in the round spaces. The solid growth pattern consists of sheets of myoepithelial cells which, in some areas, may have a spindled shape. Ductal structures are scarce and may be difficult to find. The papillary growth pattern is encountered in cystic areas. The epithelium lining the cystic spaces and papillary structures maintains a biphasic pattern with luminal duc-tal epithelial cells and abluminal clear myoepithelial cells. In all growth patterns the myoepithelial cells predominate, however, occasionally areas may be present in which apparent atrophy of the clear cells has produced "naked ducts" lined only by a single layer of epithelial cells.
Was this article helpful?