Mixed epithelial and stromal tumor of the kidney on 18F-FDG PET/CT in a 21-year-old female.

Mixed epithelial and stromal tumor of the kidney (MESTK) is a rare tumor composed of epithelium and interstitium. In radiological imaging, the masses are cystic and solid, and it is difficult to distinguish MESTK from renal cystic lesions. A final diagnosis of MESTK depends on pathology. We report this rare case of MESTK that was diagnosed in a 21-year-old woman. 18F-labeled fluoro-2-deoxy glucose (18F-FDG) positron emission tomography (PET)/computerized tomography (CT) and contrast-enhanced computerized tomography features of MESTK are presented, and could potentially provide useful information for the differential diagnoses of cystic renal neoplasms and preoperative staging of the tumor.