Methylene blue-aided cholangioscopy in patients with biliary strictures: feasibility and outcome analysis. Reply to Maetani

Abstract

We read Professor Maetani’s letter and comments about our study [1] with great interest. Maetani also reported their previous experience with methylene blue in the bile duct [2]. In their study protocol, the bile duct was analyzed by percutaneous cholangioscopy. Differences in methylene blue staining properties between cancerous and noncancerous epithelia were noted. Furthermore, endoscopic findings were compared with data on frozen sections of epithelia. Their investigation revealed that microscopic staining properties were not always significantly associated with endoscopic observations. Whereas 18 of 20 (90 %) specimens of normal epithelia revealed positive staining with methylene blue, 11 out of 16 (69 %) specimens of metaplastic epithelia were stained, with no staining obtained in cancerous epithelia. The cancerous epithelia stained significantly less often than either the normal or the metaplastic epithelia.