Collision Tumor of the Kidney: Renal Cell Carcinoma Hidden in a Giant Angiomyolipoma in a Patient With Tuberous Sclerosis Complex

Abstract

Background: A renal angiomyolipoma is a mixed mesenchymal benign tumor composed of smooth muscle, adipose tissue, and blood vessels. Malignant transformation of angiomyolipomas is anecdotal. To our knowledge, only 6 cases have been reported, and 4 of the patients had tuberous sclerosis complex diagnosed. Case Report: We present the case of a 29-year-old male with tuberous sclerosis complex who arrived at the emergency room with gross hematuria and a painful right-sided abdominal mass. Imaging studies revealed active bleeding from a giant angiomyolipoma. An emergency nephrectomy was performed. Histopathology evaluation revealed an angiomyolipoma with a focal lesion and clear cell renal carcinoma within the tumor. Conclusion: Limited evidence is available to dictate management of collision tumors of the kidney in the scenario of tuberous sclerosis complex, so a multidisciplinary approach that includes urology, oncology, genetics, and nephrology intervention needs to be considered. No standardized follow-up modality has been established for angiomyolipomas, so patients should be placed under active surveillance, similar to that carried out in cases of renal cell carcinoma.

Collision tumor of spindle cell lipoma arising from perirenal tissue and acquired cystic disease‐associated renal cell carcinoma: A rare case report

“…There have been very few reports on collision tumors. 4 , 16 , 17 , 18 , 19 , 20 To the best of our knowledge, this is the first documented case diagnosed with collision tumors comprising SCL and ACD‐RCC. It was not until immunohistochemical analysis was performed that the patient was diagnosed with collision tumors.…”

“…There have been very few reports on collision tumors 4,16–20 . To the best of our knowledge, this is the first documented case diagnosed with collision tumors comprising SCL and ACD‐RCC.…”

“…Collision tumors are a rare phenomenon that presents the coexistence of 2 histologically distinct neoplasms in the same site. 3 , 4 Here, we present a case of a man with collision tumor of SCL arising from perirenal tissue and ACD‐RCC.…”