The incidence of renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion in Saudi adult patients with renal cancer: a retrospective tissue microarray analysis.

Renal cell carcinoma (RCC) is the most common renal tumour. RCC with Xp11.2 translocation/TFE3 (transcription factor E3) gene fusions (Xp11.2 RCC) is positive for immunostain labelling by TFE3 antibody. This tumour is rarely described in adults. This study aims to evaluate the frequency of RCC with Xp11.2 in a subset of Saudi adult patients with RCC. 112 RCCs diagnosed in 1995-2016 were retrieved from the Department of Pathology at King Abdulaziz University and King and Faisal Specialist Hospital and Research Centre, Saudi Arabia. Tissue microarrays were constructed and TFE3 immunostaining was performed. TFE3 immunostaining was considered positive when diffuse strong nuclear immunostaining was detected. TFE3 immunostaining-positive tumours were confirmed by fluorescence in situ hybridisation. 4.5% of RCCs were shown to be Xp11.2 RCC by TFE3 immunostaining. TFE3-positive tumours have a papillary configuration, nested pattern, or both. Positive tumours show male predominance, more occurrences in middle age, high grade, and large-sized tumours with necrosis. Two tumours were FISH-positive. Xp11.2 RCC is rare in Saudi adult patients. Xp11.2 RCCs tend to be large sized and higher grade. TFE3 immunostaining should be considered in RCC that are histologically suggestive to confirm the diagnosis of Xp11.2.