MSH: A benign tumor characterized histologically by tall columnar epithelium within a lymphoid tissue stroma. It is usually found in the salivary glands, especially the parotid.,NCI: An adenoma characterized by an oncocytic, often papillary, epithelial component, dense lymphoid stroma, and cystic spaces. It occurs primarily in the parotid gland, and is the second most common benign parotid salivary gland tumor. A strong association with smoking has been reported. About 10% develop simultaneous or metachronous contralateral tumors. It typically presents as a painless swelling in the lower portion of the parotid gland.