[Morphological characteristics of slowly and rapidly progressing human bladder papillomas].

A total of 477 transitional cell papillomas (TP) of the urinary bladder were divided into slowly (10.9%) and rapidly progressing (89.1%) ones according to the late results of the treatment and morbid anatomic features. Over a period of ten years following the excision of rapidly progressing TP the recurrencies were noted 5-fold and malignancies 12-fold as often comparatively to slowly progressing papillomas. Such papillomas were 1 cm and less in diameter and had a narrow base. The epithelial thickness reached 7--8 cell layers, and the mitotic index 3--4 fold surpassed the normal one (0.1%). The difference in histologic and ultrastructural differentiation of basal and intermediate cells of the epithelium persisted. Rapidly progressing TP were 0.5--2 cm in diameter, the epithelial thickness often exceeded that of 8 cell layers, while the mitotic index ranged within 0.5--1.0%. There were no sign of cellular atypia. The difference in histologic and ultrastructural differentiation of basal and imtermediate cells of the epithelium was in some cases effaced. TP subdivision into slowly and rapidly progressing papillomas will contribute to the improvement of the disease prognosis and statistical recording.