A review of ALK-rearranged renal cell carcinomas with a focus on clinical and pathobiological aspects.

ALK-rearranged renal cell carcinoma (ALK-RCC) has been recently proposed and incorporated into the recent World Health Organisation Classification of renal tumours as a provisional entity. In this article, we review ALK-RCC with a focus on clinical and pathobiological aspects. Seventeen cases have been described to date. ALK-RCC accounts for less than 1% of all renal tumours. The age of patients ranges from 6 to 61 years with a mean age of 29.6 years. Grossly, the tumour forms were ill-demarcated or well demarcated solid mass in the renal medulla. Histologically, RCC with VCL-ALK translocation resembles renal medullary carcinoma and mucinous cribriform pattern, signet-ring cell pattern and solid rhabdoid pattern are often observed in RCC with non-VCL-ALK fusion. Immunohistochemically, ALK protein diffusely expresses and TFE3 is often expressed. ALK gene can fuse to VCL, TPM3, EML4, HOOK1 or STRN gene. A break-apart fluorescence in situ hybridisation study is clinically available for the practice of definite diagnosis. ALK inhibitor therapy will provide great benefit for patients with advanced stage of ALK-RCC in the near future.