Incidence, clinicopathological features and fusion transcript landscape of translocation renal cell carcinomas.

Aims: Translocation renal cell carcinoma (tRCC) is a rare subtype of kidney tumour characterized by translocations involving the transcription factor TFE3 or TFEB. tRCC was introduced into the World Health Organization classification in 2004, but much is still unknown about the natural history, clinicopathological features and outcomes of the disease. The aim of this study was to describe the landscape of fusion transcript in a large single-institution series of fluorescence in-situ hybridization (FISH)-confirmed tRCCs and then to compare it to morphological and clinical data.

Methods And Results: Paired-end RNA sequencing was performed within a prospective database of the Department of Pathology, Centre Hospitalier Régional Universitaire (Lille, France). The diagnosis of tRCC was confirmed by FISH. Among a total of 1130 identified renal cell carcinomas, 21 cases (1.9%) showed rearrangement of the TFE3 (n = 20) or (TFEB) (n = 1) gene. Median patient age was 31 years (range = 15-47), and the female-to-male ratio was 6:1. Five different TFE3 fusion transcripts were identified; the most frequent TFE3 partners were PRCC (n = 4) and SFPQ (n = 4). The other partners involved were ASPCR1 (n = 1) and MED15 (n = 1) genes as well as a novel TFE3 partner, GRIPAP1.

Conclusions: We identified a new fusion partner, GRIPAP1. The prognostic role of transcript type could not be determined because our number of cases was too small. Four patients (19%) died of the disease, all of which presented with a lymph node involvement at diagnosis. We confirm that tRCC can be an aggressive tumour, especially those of advanced clinical stage.