adenoid cystic carcinoma

carcinoma characterized by bands or cylinders of hyalinized or mucinous stroma separating or surrounded by nests or cords of small epithelial cells. It appears as one or more of three patterns: cribriform, solid, and tubular. The usual site is the salivary glands, but histologically similar tumors appear elsewhere. Malignant and invasive but slow-growing, it spreads by infiltrating the bloodstream and perineural spaces. Called also adenocystic c., cribriform c., and cylindroma. NOTE: Certain unrelated tumors may have a cylindromatous or adenoid cystic pattern, e.g., ameloblastoma.