Abstract

OBJECTIVE:

To determine whether a limited immunohistochemical panel can help differentiate metastatic colonic adenocarcinoma from primary enteric-type adenocarcinoma of the urinary tract and urothelial (transitional cell) carcinoma with glandular differentiation, which appear morphologically similar but most often necessitate different treatment protocols.

DESIGN:

We examined lower urinary tract tumors (5 urinary bladder, 2 urethral) from 7 patients with a history of colonic adenocarcinoma. The differential diagnoses in these cases included metastatic colonic adenocarcinoma, primary enteric-type adenocarcinoma of the urinary tract, and urothelial carcinoma with glandular differentiation. An immunohistochemical panel consisting of cytokeratin 7 (CK-7), cytokeratin 20 (CK-20), and villin was evaluated in all cases. Four primary enteric-type adenocarcinomas of the urinary tract and 5 conventional urothelial carcinomas were also studied to compare morphologic features and immunohistochemical staining patterns.

RESULTS:

Of the 7 cases, 6 were determined to be metastatic colonic adenocarcinoma and 1 was diagnosed as a primary urothelial carcinoma with glandular differentiation. All 6 metastatic colonic adenocarcinomas, 6 of the 7 primary colonic adenocarcinomas, and all 4 primary enteric-type adenocarcinomas of the urinary tract were CK-20 positive (1 was CK-20 negative), villin positive, and CK-7 negative. The single urothelial carcinoma with glandular differentiation and all 5 control cases of urothelial carcinoma were CK-7 and CK-20 positive, and villin negative.

CONCLUSIONS:

We conclude that (1) villin is expressed in primary enteric-type adenocarcinoma of the urinary tract; (2) in difficult cases, urothelial carcinoma with glandular differentiation can be distinguished from colonic adenocarcinoma because the former is CK-7 positive, CK-20 positive, and villin negative, whereas the latter is CK-20 positive, villin positive, and CK-7 negative; (3) clinical information is essential when evaluating lower urinary tract tumors that are clinically and morphologically similar to enteric-type adenocarcinoma of the urinary tract; and (4) the similar immunohistochemical profiles of metastatic colonic adenocarcinoma and primary enteric-type adenocarcinoma of the urinary tract may be in keeping with the hypothesis that the latter arise from intestinal metaplasia.