metastatic renal cell carcinoma presenting as a clear-cell tumor in tongue: a case report

introduction: metastatic lesions of the oral cavity are extremely rare, accounting for approximately 1% of all malignant oral tumors. the most common primary sources of metastatic tumors in the oral region are, from the most to the least common, the breast, lung, kidney, bone, and colon. renal cell carcinoma accounts for nearly 3% of all adult malignancies. it usually metastasizes to the lungs, bone, adrenal glands, and regional lymph nodes. the incidence of metastasis from renal cell carcinoma to the head and neck region is very low. the tongue is considered a very rare atypical ear, nose, and throat (ent) location for metastasis of renal cell carcinoma. the present case from iran reports tongue metastasis of renal cell carcinoma (rcc).   case report: the following report is based on an 80-year old male patient with a tongue lesion and ambiguous past medical history that ultimately leads to diagnosis of a metastatic rcc. we also updated a previous literature review that was published 2008. a histopathological differential diagnosis for clear-cell tumors is also discussed.   conclusion:  because of the rarity of metastatic tumors of the oral region as well as the presence of other lesions with clear cells, diagnosis of metastatic clear-cell rcc in the oral cavity can be very difficult and challenging.