This study was undertaken for the purpose of examining the behavior of the grossly normal-looking vesical urothelium of patients with bladder tumors.
Twenty-four bladders bearing primary tumors and twenty-four control bladders were studied. The former consist of 16 cases of transitional cell carcinoma, 3 of squamous cell carcinoma, 2 of undifferentiated cell carcinoma, 2 of urachal carcinoma and 1 of sarcoma, and the latter contain 20 normal cases and 4 of secondary vesical involvement of the cervical carcinoma.
Routine sections of the tumors and of ten pieces of normal-looking bladder mucosa were made.
Conclusions obtained are as follows:
(1) The epithelium of tumor-bearing bladders show a marked tendency to hyperplastic and metaplastic changes, as compared with those of tumor-free bladders.
Submucosal inflammation is marked in tumor-bearing bladders though it is also seen in tumor-free bladders.
(2) Hyperplastic and metaplastic changes are especially marked in the papillary tumors, but do not show a parallelism with the degree of malignancy. They are seen in distant areas from tumors as well as in adjacent areas, somewhat frequently in the latter.
(3) The changes observed are as follows:
(a) Papillary proliferation of the epithelium
It is seen in 41.7% of the tumor-bearing bladders, particularly in the papillomatosis and the papillary carcinoma, while it is not seen in bladders which bear tumors not originating from vesical epithelium such as urachal carcinoma and sarcoma, and control bladders.
(b) Deep-growing of the epithelium (including the Brunn's cell nest).
This is a change observed the most frequently, or in 75% in the tumor-bearing bladders although it is also seen in control bladders in 16.7%. This change, differing from the papillary proliferation, is equally seen in bladders with various types of the carcinoma.
(c) Cyst formation
It is seen in 45.8% of the tumor-bearing bladders and in 8.3% of the Control bladders. It is seen in bladders with every types of the tumor and does not show any relation to the adenocarcinoma.
(d) Leukoplakia
Two cases of the bladder with tumor of the squamous cell type, are accompanied with the leukoplakia, in one of which a transitional figure to the carcinoma is able to be found.
(4) These changes are characteristic of the primary and epithelial tumors of the bladder and is not so marked in nonepithelial vesical tumors such as sarcoma and urachal carcinoma, and also in secondary vesical involvement, for example, of the cervical carcinoma. They are, therefore, thought to be not secondary but primary changes in bladders with the epithelial tumors, and it is understood that the epithelium of the bladders with epithelial tumor, particularly with the papillary tumor, wholly show a predisposition to new-growth. The difficult cure of the bladder tumors by surgical treatment is accounted for by the fact that the whole epithelium of tumor-bearing bladders have proliferative changes as above-mentioned, in addition to the fact of the tendency of the bladder tumor to wide and deep infiltration in their early stage.

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