Case Report: A rare case of primary undifferentiated pleomorphic sarcoma of the renal pelvis with high PD-L1 expression and a misleading positive urine FISH
Primary undifferentiated pleomorphic sarcoma (UPS) of the renal pelvis is an extremely rare and aggressive mesenchymal malignancy. The diagnosis remains challenged, and its clinical characteristics and treatment strategies remain unclear. Urine fluores…