Novel gene fusion of <italic>PRCC–MITF</italic> defines a new member of MiT family translocation renal cell carcinoma: clinicopathological analysis and detection of the gene fusion by RNA sequencing and FISH.

Aims: <italic>MITF</italic>,<italic> TFE3</italic>,<italic> TFEB</italic> and <italic>TFEC</italic> belong to the same microphthalmia‐associated transcription factor family (MiT). Two transcription factors in this family have been identified in two unusual types of renal cell carcinoma (RCC): Xp11 translocation RCC harbouring <italic>TFE3</italic> gene fusions and t(6;11) RCC harbouring a <italic>MALAT1–TFEB</italic> gene fusion. The 2016 World Health Organisation classification of renal neoplasia grouped these two neoplasms together under the category of MiT family translocation RCC. RCCs associated with the other two MiT family members, <italic>MITF</italic> and <italic>TFEC</italic>, have rarely been reported. Herein, we identify a case of <italic>MITF</italic> translocation RCC with the novel <italic>PRCC–MITF</italic> gene fusion by RNA sequencing. Methods and results: Histological examination of the present tumour showed typical features of MiT family translocation RCCs, overlapping with Xp11 translocation RCC and t(6;11) RCC. However, this tumour showed negative results in TFE3 and TFEB immunochemistry and split fluorescence <italic>in‐situ</italic> hybridisation (FISH) assays. The other MiT family members, <italic>MITF</italic> and <italic>TFEC</italic>, were tested further immunochemically and also showed negative results. RNA sequencing and reverse transcription–polymerase chain reaction confirmed the presence of a <italic>PRCC–MITF</italic> gene fusion: a fusion of <italic>PRCC</italic> exon 5 to <italic>MITF</italic> exon 4. We then developed FISH assays covering <italic>MITF</italic> break‐apart probes and <italic>PRCC–MITF</italic> fusion probes to detect the <italic>MITF</italic> gene rearrangement. Conclusions: This study both proves the recurring existence of <italic>MITF</italic> translocation RCC and expands the genotype spectrum of MiT family translocation RCCs. [ABSTRACT FROM AUTHOR]