Tubulocystic renal cell carcinoma with poorly differentiated foci and loss of fumarate hydratase: A case report.

Tubulocystic renal cell carcinoma (RCC) is one of the newly recognized subtypes of RCC. It has a unique cystic morphology and indolent behavior. During the last decade, few studies have been published describing tubulocystic RCC with poorly differentiated foci. A subset of these cases are associated with loss of fumarate hydratase which is a characteristic feature of hereditary leiomyomatosis and renal cell carcinoma-associated RCC. However, these two entities represent two distinct subtypes of RCC in the recent WHO Classification of kidney tumors. Herein, we are describing a rare case of tubulocystic renal cell carcinoma with poorly differentiated foci and loss of fumarate hydratase.