Pathology of epithelial tumors & carcinoma in situ of bladder

We have reviewed the World Health Organization International Histological Classification of Tumors of Urinary Bladder. The classification recognizes papilloma as a distinct entity, which, although histologically benign, has a definite increased risk of progression to carcinoma. The classification further characterizes carcinomas of bladder in terms of certain features which have considerable influence on treatment, recurrence and prognosis. These are: the patterns of growth, the histology of the tumor, the grade, the pathological stage, the mode and location of spread, and the status of the remaining mucosa. We have called attention to the need for proper recognition of nonpapillary, noninvasive superficial mucosal lesions which have hitherto been dismissed as atypia and dysplasia. We have demonstrated that these lesions present a high risk for development of invasive carcinoma and recommended that the term "intraepithelial neoplasia" be employed and graded one to three to eliminate the use of terms atypia, dysplasia and CIS. We have emphasized the need for development of technics to demonstrate invasive and metastatic potential of epithelial tumors of bladder.