ABSTRACT
<p><b>BACKGROUND</b>Iodine staining during endoscopy has been successfully used to detect early carcinomatous and precancerous lesions in the esophagus, cervix, and oral cavity. The objective of this study was to determine the diagnostic accuracy of fiberoptic ductoscopy (FDS) plus in vivo iodine staining for intraductal proliferative lesions of the breast.</p><p><b>METHODS</b>We performed periodic acid-Schiff (PAS) and in vitro iodine staining on 52 and 64 specimens of benign mammary hyperplasia, respectively, and 57 and 53 specimens of ductal carcinoma in situ (DCIS), respectively. Next, FDS was performed on 177 recurrent nipple discharge patients who were randomly divided into two groups. One group was iodine-staining group in which 92 patients were randomly selected to undergo iodine staining during FDS, and the remaining 85 were assigned to the control group. Biopsy specimens of suspicious lesions were obtained and subjected to histopathological examination.</p><p><b>RESULTS</b>Following PAS staining, benign mammary hyperplasia lesions were positively stained, while negligible PAS positivity was observed in the DCIS lesions (P < 0.05). Following in vitro iodine staining, benign mammary hyperplasia specimens appeared dark brown, whereas DCIS samples appeared significantly lighter or unstained. Compared with the pathological examination results, FDS with iodine staining showed an agreement rate in the diagnosis of ductal intraepithelial neoplasia (DIN), sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and Youden index of 97.82%, 98.83%, 83.33%, 5.93, 0.014, and 0.8216, respectively; the corresponding values for FDS without iodine staining were 88.24%, 89.16%, 50.00%, 1.78, 0.217, and 0.3916, respectively.</p><p><b>CONCLUSION</b>FDS with iodine staining was superior to conventional FDS for the diagnosis of DIN and is valuable for breast cancer prevention.</p>