Answer: Leiomyomatosis associate renal cell carcinoma

Histology: The tumor consists of tubules lined by cells with clear cytoplasm. The striking finding are the huge eosinophilic nucleoli surrounded by halos. The nucleoli resemble viral inclusions.

Discussion: Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a hereditary cancer syndrome in which affected individuals are at risk for the development of uterine and skin leiomyomas and renal cell cancers. These renal tumors are solitary with an aggressive behavior. Many of these tumors have a predisposition for local invasion and metastases to regional and distant lymph nodes, including the cervical chain. The disease is inherited as an autosomal dominant condition with incomplete phenotype penetrance, and germline mutations in the fumarate hydratase gene has been found to predispose to this syndrome. Recognition of the morphologic spectrum of renal tumors in HLRCC syndrome is crucial for appropriate diagnostic genetic testing, early diagnosis, and cancer prevention of individuals at risk.

Hereditary papillary RCC and clear cell papillary RCC are characterized by low grade nuclei in contrast to the current case. Translocation associated RCC could be in the differential diagnosis, except that it lacks the characteristic nucleoli seen with HLRCC. Immunohistochemistry for TFE-3 was performed in the current case and was negative, also helping to rule out a translocation associated RCC.