Case History
Images are from a 61-year-old male with 12 cm renal mass involving renal vein, sinus and perirenal fat.
Which statement is false regarding this case?
A. IHC for FH or 2-SC are recommended
B. This is a Type 2 Papillary RCC, no studies needed
C. TFEB-amplified RCC is in the ddx
D. MART1 expression by this tumor would not be a surprise
Answer: B
Discussion:
This case showed a TFEB (11q12) amplification by FISH and is thus a TFEB-amplified renal cell carcinoma, an emerging entity. While lacking specific histologic features, TFEB-amplified renal cell carcinomas (RCC) often feature high-grade carcinoma with eosinophilic cytoplasm arranged in nested, pseudopapillary and papillary growth patterns. These neoplasms may show variable expression of TFEB, MART1, Cathepsin K and HMB45 by immunohistochemistry. These cases have so far been associated with an aggressive clinical course.
The differential diagnosis of TFEB-amplified renal cell carcinoma includes conventional renal cell carcinomas which can frequently show eosinophilic cytoplasm, as well as hereditary leiomyomatosis and renal cell carcinoma-associated renal cell carcinoma (HLRCC). The absence of diffuse CA-IX expression and presence of TFEB-amplification and variable melanocytic marker expression would exclude the former, while retention of fumarate hydratase expression and lack of modified cysteine-S-(2-succino) cysteine (2SC) labeling would exclude the latter. High-grade Type 2 papillary renal cell carcinoma is in the differential diagnosis but this is really a ‘waste basket’ category of various entities and thus a diagnosis of exclusion. TFEB-translocated RCC, a member of the MiT family of translocation RCC, often shows biphasic morphology with foci of basement membrane production and features rearrangement, not amplification, of the TFEB gene.
Argani P et al. American Journal of Surgical Pathology. 2016; 40 (11): 1484-1495.
Case contributed by: Todd Stevens, M.D., Associate Professor, Anatomic Pathology