Warthins tumour is -

"Warthin's tumor, or papillary cystadenoma lymphomatosum, is the second most common benign parotid tumor and occurs most often in older white men. Because of the high mitochondrial content within oncocytes, the oncocyte-rich Warthin tumor and oncocytomas will incorporate technetium Tc 99m and appear as hot spots on radionuclide scans. If fine-needle aspiration suggests a slow-growing Warthin tumor with confirmatory technetium scanning in a patient with contraindications to surgery, the tumor may be closely monitored because it has no malignant potential." -Sabiston