Fig. 3

Histological findings of the resected tumor. a Scanning view of a hematoxylin and eosin-stained section showed a polypoid and lobulated tumor arising from the ureteral mucosa. b A relatively clear border was observed in the periphery of the lesion (×100). c Subepithelial condensation of stromal cells was noted (×200). d Stromal cells were spindle-shaped and stellate in appearance, and no conspicuous cytological atypia or mitoses were found in the stroma (×400). e Active mitosis was detected in areas with moderate dysplasia (×400). f Some abnormal giant cells (white arrows) and early infiltration (black arrows) were detected in areas with severe dysplasia (×400). At high magnification, the microinvasive carcinoma component was composed of irregular nests of oval epithelial cells with abundant eosinophilic cytoplasm (f, left lower)