TFEB Amplification Renal Cell Carcinoma Detected by Chromosome Genomic Array Testing: A Case Report for Diagnosis of a Novel Entity

Background: The accurate diagnosis and corresponding prognosis of renal cell carcinoma (RCC) are challenged by overlapping histological features and imprecise immunohistochemical (IHC) markers, which easily leads to misdiagnosis of rare subtypes, such as translocation RCC (tRCC). Case presentation: We report here a rare case of TFEB amplified RCC presenting in a 47-year-old male with a 10 cm renal mass and regional lymph node metastases. This tumor was initially diagnosed as a clear cell RCC (ccRCC). However, chromosome genomic array testing (CGAT) revealed TFEB gene amplification, which was confirmed by fluorescent in situ hybridization (FISH). TFEB transcript overexpression was demonstrated by RNA in situ hybridization. The tumor histology was reassessed and relabelled as unclassified RCC based on unusual histologic features and a non-specific IHC profile. The tumor rapidly progressed with distant metastatic disease that responded to treatment with sunitinib for 11 months. Conclusions: TFEB gene amplification without rearrangement/translocation appears to be a novel entity. Ours is a rare TFEB gene amplification RCC case with metastasis and unusual morphology. The workup of our case demonstrates the potential role for CGAT to aid in the subtype classification of RCC tumors.