Warthin tumor (MONDO_0006493) is 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. It typically presents as a painless swelling in the lower portion of the parotid gland. Also known as: Warthin's tumor, Warthin's tumour, adenolymphoma.