Fig. 2

Hematoxylin–eosin (HE) staining of papillary renal neoplasm with reverse polarity (PRNRP) and urothelial carcinoma (UC). a PRNRP coexisting with an adjacent UC (HE × 20, HE × 100). b Branching papilla with inverted low-grade nucleus of PRNRP (HE × 200). c Eosinophilic ‘hobnail cells’ in the PRNRP (HE × 200). d Intracytoplasmic vacuoles and hemosiderin deposition in the PRNRP (HE × 400). e Small focal invasions into the renal parenchyma in the PRNRP (HE × 100). f Hemorrhage can be seen in the local interstitium of PRNRP. (HE × 50). g A small amount of lymphocyte infiltration locally in the interstitium of the PRNRP. (HE × 200). h UC showed papillary growth, an increased number of cell layers, disordered polarity, mild atypia of the cells with an occasional mitotic division (HE × 200, HE × 400)