Immunophenotype of high-grade prostatic adenocarcinoma and urothelial carcinoma

Morphologic features alone can usually be used to distinguish prostatic ade nocarcinoma and urothelial carcinoma of the urinary bladder. Poorly differe ntiated tumors, however, can occasionally have features of both neoplasms, making determination of site of origin difficult, No study has provided a p anel of antibodies to assist in the distinction of these two tumors. For th is study, 73 examples of moderately and poorly differentiated prostatic ade nocarcinoma and 46 examples of high-grade urothelial carcinoma were obtaine d from radical resection specimens. Immunohistochemical studies were perfor med using the following panel of antibodies: cytokeratin (CK) 7, CK 20, 34 beta E12 Leu M1, carcinoembryonic antigen (CEA)m, CEAp, p53, Leu 7, prostat e-specific acid phosphatase (PSAP), prostate-specific antigen (PSA), and B7 2.3. Mucicarmine was also performed. Intermediate and high-grade prostatic carcinoma were compared and then high-grade prostatic carcinoma was compare d with high-grade urothelial carcinoma PSA and PSAP each stained 94% of pro static adenocarcinomas, but no urothelial carcinomas. Leu 7 stained 94% of prostate and 17% of urothelial carcinomas. Over half of the urothelial carc inomas showed positivity for 34 beta E12 (65%), as did two cases of prostat ic carcinoma (6%). Eighty-three percent of urothelial carcinomas and 12% of prostatic adenocarcinomas stained with CK 7. Forty-one percent of urotheli al carcinomas and 12% of prostatic carcinomas were reactive for CEAm, and p 53 stained 33% and 3% of urothelial and prostatic adenocarcinomas, respecti vely. No significant difference was seen in the expression of CEAp, CK 20, B72.3, Leu Mi, or mucicarmine between prostate and urothelial carcinoma We propose a panel of six antibodies to assist in the distinction of high-grad e prostatic adenocarcinoma from high grade urothelial carcinoma: PSA, PSAP, 34 beta E12 Leu 7, CK7, and p53. The first three antibodies should be used initially; if results are negative, the remaining antibodies may be employ ed.