Figure 3. H&E section of the bladder TURB shows infiltration by nests of malignant polygonal cells with clear to pale eosinophilic cytoplasm, separated by a fine vascular network. (E, F) Immunohistochemistry supports the diagnosis of metastatic clear cell renal cell carcinoma, with positive staining in the tumor cells for RCC and vimentin (A), and PAX8 (B). Negative staining for PSA (C) rules out a prostate origin, and negative staining for GATA3 (D) rules out a bladder origin.

H&E: hematoxylin and eosin, TURB: transurethral resection of bladder, RCC: renal cell carcinoma, PAX8: paired box gene 8, PSA: prostate-specific antigen, GATA3: GATA-binding protein 3