Primary retroperitoneal renal cell carcinoma associated with transcription EB gene fusion.

Background: Renal cell carcinoma (RCC) with the distinct type of t(6;11) (p21;q12) translocation (transcription factor EB, TFEB) is a rare neoplasm. It is even less when talks about primary retroperitoneal TFEB RCCs. To our knowledge, no previous literature has been reported about this kind of RCCs. In this article, we report a case of primary retroperitoneal renal cell carcinoma associated with transcription EB gene fusion.

Methods: A 73-year-old male patient presented with a retroperitoneal mass for more than one month.

Results: Pathologically, the mass was soft and colorful, tumor cells showed a biphasic morphology characterized by nests of larger epithelioid cells surrounding intraluminal collections of smaller cells clustered around basement membrane materia. These tumor cells were positive for Pax-8, EMA, TFEB, CK, P504S, Vimentin and CD10 on immunohistochemical stain, and positive for TFEB on fluorescence in situ hybridization assay.

Conclusions: We reported the first case of primary retroperitoneal renal cell carcinoma associated with transcription EB gene fusion. The pathological feature of the case we reported was very typical. The best treatment at presentation is the total resection. Long-term follow-up study is needed in order to acquire better diagonitic quality and fulfill diagnostic requirements.