Epithelial abnormalities of urinary bladder.

We have called attention to certain epithelial lesions of the bladder characterized as proliferative, metaplastic, and neoplastic. In the first group are included hyperplasia, von Brunn's nests, papillary cystitis, papilloma and inverted papilloma. The second category includes squamous metaplasia, mucous metaplasia, and tubular metaplasia. These two categories, while benign, are indicative of agitated sick mucosa and may progress to neoplasia. The neoplastic changes consist of carcinoma involving the surface epithelium, von Brunn's nests, papillary cystitis, and/or cystitis cystica.