Correlation of histopathological, cytological and flow cytometric findings in neoplastic and nonneoplastic lesions of the bladder.

Biopsy diagnosis, urine cytology and flow cytometry features of urine and bladder washings were compared in 81 cases of benign and malignant bladder disease. Some patients were followed by urine cytology and flow cytometry during treatment of tumors. There was a good correlation of the 3 parameters in relatively high grade tumors (II and III) but an inconsistent appearance of cells in the urine diagnosable by either urine cytology or flow cytometry for low grade lesions. High grade flat neoplasms may be detectable by urine cytology and flow cytometry before they are visible on endoscopy. Flow cytometry may indicate urothelial proliferation before it is apparent on urine cytology. Exfoliative benign lesions are diagnosed readily by the combination of urine cytology and flow cytometry. In benign and malignant lesions shedding of viable cells and, therefore, accessibility to urine cytology and flow cytometry are inconsistent. The need for repeated examinations in the case of low grade lesions suggests that the method is not reliable for single test screening programs but it is a valuable means of followup in cases of suspected or diagnosed disease.