[Histological study of cases of bladder cancer and chronic cystitis with difficulty in cystoscopic diagnosis].

Twenty-seven cases in which cancer could not be distinguished from chronic cystitis were reviewed. These cases were divided into those with and those without a past history of bladder tumor. The high frequency of hyperplasia in the group with a history of bladder tumor suggested that hyperplasia may be a precursor of papillary tumor. On the other hand, proliferative lesions such as cystitis cystica and metaplasia were encountered in the group with no history of bladder tumor and 50 percent had symptoms of chronic cystitis. These findings suggested that proliferative lesions in the bladder developed by inflammatory irritation. Urinary cytology was done in 18 cases. Cytology was positive in 2 of the 3 cases of transitional cell carcinoma. Therefore, urinary cytology was useful, but it did not provide distinction in two cases of follicular cystitis and a case of squamous metaplasia was false positive.