Objective To investigate the imaging characteristics of renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion.

Methods We retrospectively analyzed the clinical and imaging data of five children with Xp11.2 tRCC confirmed by surgery and pathology in our hospital from January 2015 to December 2020. Four cases underwent CT plain scan and contrast-enhanced examination, and one case underwent MRI plain scan, contrast-enhanced examination and DWI examination. We observed and analyzed the location, size, shape, boundary, composition, enhancement pattern and degree, the relation with the renal hilum and adjacent large vessels, and the metastasis of the tumor.

Results All cases were cortical-medullary type. Four cases were solid/cystic-solid lesions, iso- or slightly hyper-density on CT scans with calcification and necrosis, in which a few with bleeding or cystic lesions. Enhanced scanning primarily showed mild to moderate enhancement, and enhancement of pseudocapsule was seen during the delayed phase. One case was cystic lesion, the cystic fluid presented as hypo-density on CT, and T1 hypo-intensity and T2 hyper-intensity, as well as restricted diffusion on DWI. No enhancement was found in the cystic part after enhancement. There were irregular and thickened cystic wall and septum, and mural nodules on enhanced MRI.

Conclusion Several characteristics of Xp11.2 tRCC in children could be drawn. Punctate and patchy calcifications in or around the solid/cystic-solid lesions and delayed "pseudocapsule sign" are typical. The possibility of Xp11.2 tRCC should be considered when there are irregular and thickened cystic wall and septum and the enhancement of mural nodules.