Fig. 2

H&E and immunohistochemical (IHC) staining in 3 cases of prostate cancer involving the rectal wall. A. IHC staining confirmed the diagnosis of prostate cancer in case 1 (all images, except a, are of IHC staining, magnified × 200). a. H&E staining of case 1 (Gleason score 5 + 4). b. Strong positive expression of CK in prostate cancer and mucosal epithelial cells. c and d. The cancer cells are strongly positive for PSA and P504s, whereas the epithelial cells of the rectal mucosa are negative. e. The cancer cells are negative for CDX2. B. IHC staining confirmed the diagnosis of prostate cancer in case 2 (all images, except a, are of IHC staining, magnified × 200, except b, magnified × 100). a. H&E staining of case 1 (Gleason score 4 + 3). b. Positive expression of CK in cancer cells. c. Strong positive expression of PSA in cancer cells with no expression in rectal epithelial cells. d. Strongly positive expression of P504s in cancer cells. e. The cancer cells are negative for villin. C. IHC staining confirmed the diagnosis of prostate cancer in case 3 (all images, except a, are of IHC staining, magnified × 200). a. H&E staining in case 3 (Gleason score 4 + 4). b. The cancer cells are weakly positive for CK and the epithelial cells are strongly positive. c and d. The cancer cells are strongly positive for PSA and P504s. e. The cancer cells are negative for CK20