Unusual presentation of mixed epithelial and stromal tumor of ureter posing diagnostic dilemma

The mixed epithelial and stromal tumor (MEST) family comprises a spectrum of tumors varying from predominantly cystic tumors such as adult cystic nephroma, to variably solid tumors such as MESTs. These rare renal tumors typically affect women in their perimenopausal age. Most of these tumors are benign; however, at some rare occasions, they are associated with malignant transformation. The current article reports a rare case of MEST arising from the proximal ureter in a perimenopausal woman, manifested as a cord-like structure in the ureter, and posing the diagnostic dilemma.