Value of a panel of antibodies to identify the primary origin of adenocarcinomas presenting as bladder carcinoma

Aims: Adenocarcinomas may arise primarily from the urinary bladder, but secondary involvement from adenocarcinomas arising in adjacent organs is more common. In the present study we tried to differentiate primary urinary bladder adenocarcinomas from adenocarcinomas arising from the surrounding organs, based on their antigen profiles in routinely processed, paraffin‐embedded tissue specimens. We analysed the staining results using stepwise linear discriminant analysis. Methods and results: We investigated the usefulness of a panel of antibodies against cytokeratin 7, E48, cytokeratin 20, PSA, PSAP, CEA, vimentin, OC125 and HER‐2/neu, to discriminate primary bladder adenocarcinoma from adenocarcinomas arising from the prostate, urachus, colon, cervix, ovary and endometrium. In the differential diagnosis with urinary bladder adenocarcinoma, an overall correct classification was reached for 77% and 81% of urachal and colonic carcinomas, respectively, using CEA, for 93% of prostatic adenocarcinomas using PSA, for 82% and 70% of cervical and ovarian adenocarcinomas, respectively, using OC125, and for 91% of endometrial adenocarcinomas using vimentin. Adding other antibodies did not improve the classification results for any of these differential diagnoses. Conclusions: For the surgical pathologist, a panel of antibodies consisting of CEA, PSA, OC125 and vimentin is helpful to differentiate primary urinary bladder adenocarcinomas from adenocarcinomas originating from prostate and endometrium, less helpful in differentiation with urachal carcinoma, and not helpful in differentiation with colonic, cervical and ovarian carcinoma.