We tried to classify non-muscle-invasive papillary high-grade UTUC using IHC staining for CK5/6 and CK20 as surrogate markers, which were known to be related to molecular subtypes and to the prognosis of UTUC and of urinary bladder carcinoma [19,20,21,22]. Here, KRT20 is linked to renal pelvis/ureter urothelial carcinoma.