TFEB rearranged renal cell carcinoma. A clinicopathologic and molecular study of 13 cases. Tumors harboring MALAT1-TFEB, ACTB-TFEB, and the novel NEAT1-TFEB translocations constantly express PDL1.

Renal cell carcinomas with t(6;11) chromosome translocation has been classically characterized by the rearrangement of the TFEB gene, located on chromosome 6, and MALAT1 gene, located on chromosome 11. Recently, a few other genes have been described as fusion partners in TFEB rearranged renal cell carcinomas. Although most of TFEB rearranged renal cell carcinomas have an indolent behavior, in the rare cases of advanced metastatic disease targeted therapy and predictive markers remain lacking. In the present study, we collected 13 TFEB rearranged renal cell carcinomas, confirmed by FISH, analyzing their morphology and exploring the novel gene partners. Looking for predictive markers, we have also performed PDL1 immunohistochemical analysis by using four different assays (E1L3N, 22C3, SP142, and SP263). MALAT1 gene rearrangement has been found in ten tumors, five cases showing classical biphasic morphology with "rosettes", five cases without "rosettes" mimicking other renal cell carcinomas or epithelioid angiomyolipoma/pure epithelioid PEComa. We identified two different partner genes, ACTB and NEAT1, the latter previously unreported and occurring in a tumor with an unusual solid and cystic appearance. In both cases, the "rosettes" were absent. In one case no gene partner was identified. Overall, in 12 of 13 TFEB-rearranged renal cell carcinomas staining for PDL1 SP263 was observed, whereas the other antibodies were less reliable or more difficult to interpret. In conclusion, we described the third case of ACTB-TFEB rearranged renal cell carcinoma and a novel NEAT1-TFEB rearranged renal cell carcinoma, both without the distinctive biphasic morphology typical of t(6;11) renal cell carcinoma. Finally, PDL1 SP263 was constantly expressed in TFEB rearranged renal cell carcinoma with possible clinical benefit which requires further investigations.

TFE3 and TFEB-rearranged renal cell carcinomas: an immunohistochemical panel to differentiate from common renal cell neoplasms.

TFE3/TFEB-rearranged renal cell carcinomas are characterized by translocations involving TFE3 and TFEB genes. Despite the initial description of typical morphology, their histological spectrum is wide, mimicking common subtypes of renal cell tumors. Thus, the diagnosis is challenging requiring the demonstration of the gene rearrangement, usually by FISH. However, this technique is limited in most laboratories and immunohistochemical TFE3/TFEB analysis is inconsistent. We sought to identify a useful immunohistochemical panel using the most common available markers to recognize those tumors. We performed an immunohistochemical panel comparing 27 TFE3-rearranged and 10 TFEB-rearranged renal cell carcinomas to the most common renal cell tumors (150 clear cell, 100 papillary, 50 chromophobe renal cell carcinomas, 18 clear cell papillary renal cell tumors, and 50 oncocytomas). When dealing with neoplasms characterized by cells with clear cytoplasm, CA9 is a helpful marker to exclude clear cell renal cell carcinoma. GATA3, AMACR, and CK7 are useful to rule out clear cell papillary renal cell tumor. CK7 is negative in TFE3/TFEB-rearranged renal cell carcinoma and positive in papillary renal cell carcinoma, being therefore useful in this setting. Parvalbumin and CK7/S100A1 respectively are of paramount importance when TFE3/TFEB-rearranged renal cell carcinoma resembles oncocytoma and chromophobe renal cell carcinoma. Moreover, in TFEB-rearranged renal cell carcinoma, cathepsin K and melanogenesis markers are constantly positive, whereas TFE3-rearranged renal cell carcinoma stains for cathepsin K in roughly half of the cases, HMB45 in 8% and Melan-A in 22%. In conclusion, since TFE3/TFEB-rearranged renal cell carcinoma may mimic several histotypes, an immunohistochemical panel to differentiate them from common renal cell tumors should include cathepsin K, CA9, CK7, and parvalbumin.