<prompt> Which of the following parotid gland tumor shows a hot spot on tc99 pertechnate scan?adenolymphomaadenoidcystic caacinic cell caAdenocarcinoma  <response>: 99mTc pertechnetate ion is distributed like Cl- and is concentrated in the salivary glands and then secreted in the saliva. Therefore sodium pertechnetate Na99mTcO4 is used to;a scan the salivary glands, especially the parotids; andb assess salivary gland function.All salivary tumours produce a cold spot on 99mTc technetium scan except adenolymphoma Warthins tumour and Oncocytoma. They take up more isotope than the rest of the gland to give a hot spot on the scan, so that a definite pre-operative diagnosis can be made without biopsy 