Image Description
Urothelial carcinoma-in-situ involving Brunn's nests in the superficial lamina propria. Uninvolved nests are present on the lower left and bottom of the image. This feature may be overdiagnosed as invasion. Brunn nests with urothelial CIS can be recognized by their round contours and the lack of stromal changes or retraction artifact around them. See higher magnification in the next image.