Optical biopsy of human bladder neoplasia with in vivo confocal laser endomicroscopy.

PURPOSE Confocal laser endomicroscopy is a new endoscopic imaging technology that could complement white light cystoscopy by providing in vivo bladder histopathology. We evaluated confocal laser endomicroscopy by imaging normal, malignant appearing and indeterminate bladder mucosa in a pilot study. MATERIALS AND METHODS Patients scheduled to undergo transurethral resection of bladder tumors were recruited during a 3-month period. After standard cystoscopy fluorescein was administered intravesically and/or intravenously as a contrast dye. A 2.6 mm probe based confocal laser endomicroscope was passed through a 26 Fr resectoscope to image normal and abnormal appearing areas. The images were collected with 488 nm excitation at 8 to 12 frames per second. The endomicroscopic images were compared with standard hematoxylin and eosin analysis of transurethral resection of bladder tumor specimens. RESULTS Of the 27 recruited patients 8 had no cancer, 9 had low grade tumors, 9 had high grade tumors and 1 had a low grade tumor with a high grade focus. Endomicroscopic images demonstrated clear differences between normal mucosa, and low and high grade tumors. In normal urothelium larger umbrella cells are seen most superficially followed by smaller intermediate cells and the less cellular lamina propria. In contrast, low grade papillary tumors demonstrate densely arranged but normal-shaped small cells extending outward from fibrovascular cores. High grade tumors show markedly irregular architecture and cellular pleomorphism. CONCLUSIONS We report the first study to our knowledge of in vivo confocal laser endomicroscopy in the urinary tract. Marked differences among normal urothelium, low grade tumors and high grade tumors were visualized. Pending further clinical investigation and technological improvement, confocal laser endomicroscopy may become a useful adjunct to conventional cystoscopy.