Squamous metaplasia of the rectum associated with ulcerative colitis diagnosed using narrow-band imaging

Abstract

A 61-year-old-man with ulcerative colitis attended our hospital for a surveillance colonoscopy. He had been diagnosed with left-sided ulcerative colitis, which had been well controlled by oral 5-aminosalicylic acid for 6 years. No active inflammation was detected in the colon or rectum at colonoscopy, but a small whitish area with a clearly demarcated border, about 5 mm in size, was found in the lower part of rectum ([Fig. 1]). Small reddish spots were seen within the whitish area, which was surrounded by hyperplastic normal rectal mucosa. Chromoendoscopy using 0.4 % indigo carmine dye highlighted the demarcation line of the whitish area ([Fig. 2]). Narrow-band imaging showed dark-brown dots corresponding to the reddish spots seen in the conventional view, and these were considered to resemble the intraepithelial capillary loops observed in normal esophageal squamous epithelium ([Fig. 3]) [1]. A biopsy specimen was taken from the whitish area for histological evaluation, and this was reported as squamous-cell epithelium without dysplasia. A final diagnosis of squamous metaplasia associated with ulcerative colitis was made.