Xp11 translocation renal cell carcinomas (RCCX1) are a group of neoplasms distinguished by chromosomal translocations with breakpoints involving the TFE3 gene within tumor cells. The result is a TFE3 transcription factor gene fusion with 1 of multiple reported genes including ASPRCR1 (606236) on chromosome 17q25 and PRCC (179755) on 1q21, and more rarely, NONO (300084) on Xq13, SFPQ (605199) on 1p34, CLTC (118955) on 17q23, and unknown genes on chromosomes 3 and 10. Xp11 translocations are often found in pediatric tumors and less commonly in adults. However, adult cases may outnumber pediatric cases since renal cell carcinoma is more common in the adult population. Prior chemotherapy is a known risk factor for Xp11 translocations. Histology shows both clear cells and papillary architecture, often with abundant psammoma bodies, although variable histologic features have been observed (review by Ross and Argani, 2010). For a discussion of genetic heterogeneity of renal cell carcinoma, see RCC (144700). [from OMIM]