Low-grade cribriform cystadenocarcinoma of the parotid gland: a neoplasm with favorable prognosis, distinct from salivary duct carcinoma.

Low-grade cribriform cystadenocarcinoma of salivary glands is a recently described rare tumor with favorable prognosis. This study reports the case of 50-year-old woman with swelling lasting for 9 months in the right parotideomasseteric area. Grossly, the tumor was well circumscribed and dominated by cystic space. Microscopically, the neoplasm consisted of well-demarcated islets, some of them cystically dilated. The architecture of islets varied from solid to cribriform and micropapillary without comedo-type necroses. The tumor cells featured no significant cytologic atypia. Immunohistochemically, luminal cells showed expression of cytokeratins (CK), CK7, CK18, and S100 protein. In addition, immunostains for CK5/6, CK14, p63 protein, and smooth muscle actin displayed a continuous rim of myoepithelial cells around all tumor nests. In contrast, detection of CK20, hormonal receptors (androgen, estrogen, and progesterone), epidermal growth factor receptor and Her-2/neu oncoprotein was negative. The patient is free of disease for 2 years. The relationship between low-grade cribriform cystadenocarcinoma and salivary duct carcinoma is discussed.