Background: In previous studies in the high risk population of Linxian, China, the majority of foci of high grade (moderate and severe) squamous dysplasia (HGD) and invasive squamous carcinoma (CA) of the esophagus were associated with endoscopically visible lesions that could be targeted for biopsy, but some foci of HGD were missed by routine endoscopic examination. This study examined whether spraying the mucosa with Lugol's iodine solution, which stains normal epithelium brown but leaves dysplasia and carcinoma unstained, could improve endoscopic detection and delineation of these lesions.
Methods: Two hundred twenty-five Linxian adults with balloon cytologic evidence of dysplasia or carcinoma underwent endoscopy. All visible lesions were described and photographed before and after staining with 1.2% Lugol's iodine solution. Biopsies were taken from all lesions visible before staining, from all unstained lesions (USLs) after applying the stain, and from representative control areas of stained mucosa.
Results: Two hundred fifty-three USLs and 255 control sites were biopsied. No complications occurred. Ninety-four biopsy sites contained HGD and 20 contained CA. Before staining, the sensitivity of visible lesions for identifying HGD or CA was 62%, and the specificity was 79%. After staining, the sensitivity of USLs for identifying HGD or CA was 96%, and the specificity was 63%. Eighty-eight percent of the HGD and CA lesions were larger or more clearly defined after staining. The diagnostic lesions in 17 of 31 patients with moderate dysplasia (55%), 8 of 35 patients with severe dysplasia (23%), and none of the 19 patients with invasive carcinoma (0%) were identified only after staining.
Conclusions: Mucosal iodine staining improved endoscopic detection and delineation of HGD and CA in these patients. This simple technique is highly sensitive for identifying these precursor and invasive squamous lesions, and it should be used whenever optimal visualization of squamous mucosal abnormalities is required.