RBM10–TFE3 renal cell carcinoma characterised by paracentric inversion with consistent closely split signals in break‐apart fluorescence in‐situ hybridisation: study of 10 cases and a literature review.

Aims: Xp11 rearrangement in renal cell carcinoma (RCC) typically involves gene fusion to the gene encoding transcription factor E3 (TFE3), a member of the microphthalmia‐associated transcription factor family on chromosome Xp11.2. Dual‐colour break‐apart fluorescence in‐situ hybridisation (FISH) is recommended to confirm histological diagnoses. Recently, RNA‐binding motif protein 10 (RBM10), encoded by a gene on chromosome Xp11.3, was identified as a chimeric partner of TFE3; thus, RBM10–TFE3 fusion results from paracentric inversion. RBM10–TFE3 RCC may yield a false‐negative result in FISH analysis of TFE3 expression. The aim of the present study was to investigate the clinicopathological features of RBM10–TFE3 RCC. Methods and results: Ten patients with RBM10–TFE3 RCC aged 31–71 years were investigated. Histological analysis, immunostaining, dual‐colour break‐apart FISH for TFE3, reverse transcription polymerase chain reaction and sequencing analysis were performed. No patient had a history of exposure to chemotherapy. Two of these patients died of RCC, and three were alive but developed metastases. Microscopically, the tumours were composed of a mixed architecture of tubulocystic and papillary patterns with scattered psammoma bodies. The tumours showed strong nuclear immunoreactivity for TFE3. FISH showed consistent closely spaced split signals in the RCCs of four patients, and polysomic signals with occasional closely spaced split signals in the RCCs of six patients. Of the latter six patients, five had renal failure, and four developed tumours in kidneys subjected to haemodialysis. Conclusions: The present study suggests that the carcinogenesis of RBM10–TFE3 RCC in some, but not all, patients may be associated with chronic kidney disease. The aggressive nature of RBM10–TFE3 RCC should be considered, as five patients experienced metastases. [ABSTRACT FROM AUTHOR]