TFE3-rearranged renal cell carcinoma with tumour thrombus in the ureter mimicking invasive transitional cell carcinoma

Abstract

Background: Renal cell carcinoma (RCC) occasionally breaches the urothelial tissue barrier and extends into the collecting system mimicking a transitional cell carcinoma. We present a case of a TFE3-rearranged renal cell carcinoma in a young patient that extended to fill the entire upper urinary tract leading to a pre-operative diagnosis of upper tract urothelial carcinoma (UTUC) based on CT imaging. A sequential algorithm of IHC/FISH assays led to the correct diagnosis of TFE3-rearranged RCC. Awareness of this potential misdiagnosis, particularly in young patients, can mitigate significant morbidity.

Keywords

• TFE3 renal cell carcinoma
• Immunohistochemistry
• Urothelial carcinoma