PREMALIGNANT AND EARLY MALIGNANT LESIONS OF THE BLADDER
The first session of the conference defined the spectrum of putative premalignant and early malignant lesions of the bladder. Two distinct non-invasive lesions were discussed which have different clinical and biologic potential. The first, carcinoma in siru, was discussed by Farrow, who noted that this lesion has the morphologic features of carcinoma, but lacks architectural alterations (is flat). DNA analysis has shown that this lesion exhibits a higher level of aneuploidy than muscle-invasive transitional cell carcinoma, underscoring its malignant potential. The second, non-invasive papillary tumors, was discussed by Melamed, who noted that this lesion can appear as a rare solitary benign papilloma, common low grade "hyperplastic papilloma," or cytologically malignant papillary carcinoma. Papillary tumors and carcinoma in siru may co-exist, and recurrences of either lesion may be seen in other parts of the urinary tract, including the renal pelvis, ureters, and urethra.
Bostwick presented a literature review of the natural history of these two lesions and early invasive carcinoma (invasion into the lamina propria) in patients predominantly treated with surgery. Predictive factors