Salivary gland, Warthin tumour

Warthin tumour is the second most common benign tumour of the parotid. It usually presents as a painless swelling of the parotid gland, although it can occur bilaterally and less commonly in minor salivary glands. It is characterized by dense lymphoid stroma, and cystic-to-papillary spaces lined by cells with abundant eosinophilic cytoplasm ("oncocytic" epithelium). This appearance corresponds to abundant mitochondria within the cell.