An ultrastructural and morphometric study of bladder tumours (III).

Quadrant biopsies were taken at cystoscopy from 12 male patients previously diagnosed on light microscopy as having flat carcinoma in situ (CIS) of the urinary bladder. There was also material available from 3 cystectomy specimens with widespread CIS associated with papillary or solid urothelial tumours. Sections of normal ureter from kidney transplant donors and biopsies from two patients investigated for non-malignant bladder conditions severed as controls. The biopsies from 4 patients were classified as mild dysplasia of the urothelium, while those from 11 patients were categorised as CIS. Biopsies categorised as mild dysplasia on light microscopy showed an increase in the number of cells with large nuclei and nucleoli when compared to controls. The number of desmosomes was significantly reduced compared to controls, while the frequency of abnormalities of the basal lamina was increased. These features were more pronounced in the CIS group. Biopsies from the CIS group could be divided into "classical" and "large cell" CIS, the latter showing a higher frequency of ultrastructural abnormalities than the "classical" type. The patients diagnosed as having CIS fell into two clinical categories, the "early onset" and the "late onset" group. The five patients in the former had been diagnosed as having CIS with or without urothelial tumours elsewhere within 3 months of presentation. In the remaining four patients CIS was observed after recurring episodes of papillary or solid tumours during the previous 9 months to 20 years. The biopsies of 3 out of 5 patients with early onset CIS had been classified "large cell" CIS, whereas only one patient out of 4 in the late onset group came into this category. An early appearance of CIS is thought to have a worse prognosis, and it is therefore suggested that "large cell" CIS is a more severe form of the disease.