Mixed Epithelial and Stromal Tumor of the Kidney Mimicking Malignancy on 18F-FDG PET/CT in a Patient With Breast Cancer

: Mixed epithelial and stromal tumor of the kidney (MESTK) is a rare renal tumor composed of solid and cystic components. Mixed epithelial and stromal tumor of the kidney has no pathognomonic imaging feature. It is difficult to distinguish MESTK from other cystic renal neoplasms using current radiological methods. We report a rare case of MESTK that was diagnosed in a 46-year-old woman with breast cancer. F-FDG PET/CT and contrast-enhanced CT features of MESTK are presented, which could potentially provide useful information in the differential diagnoses of cystic renal neoplasms.