LAUSR

Appendiceal mucinous neoplasms are the second most common tumors after carcinoid tumors in all excised appendices [1]. Low-grade appendiceal mucinous neoplasms are often found incidentally (~50%), first discovered on radiography, endoscopy, or during surgery [2]. On endoscopy, they often appear as submucosal tumor-like elevations at the appendicular orifice [3]; there are no reports of associated epithelial changes. Herein we report two cases of endoscopically observed epithelial changes in low-grade appendiceal mucinous neoplasms (▶Video 1). Case 1: A 72-year-old woman underwent colonoscopy for contrast accumulation in the appendix on 18F-fluorodeoxyglucose positron emission tomographycomputed tomography (▶Fig. 1 a, b, c). Colonoscopy revealed a slightly elevated whitish lesion covered with a mucus cap in the cecum at the appendiceal orifice (▶Fig. 2 a, b). Magnifying narrow-band imaging (NBI) showed no vessel pattern and regular, wavy, elongated surface structures (▶Fig. 2 c). Using chromoendoscopy with indigo carmine, the boundary of the lesion was clearly visualized (▶Fig. 2d). Magnifying red dichromatic imaging with indigo carmine clearly showed regular, wavy, elongated, branched surface structures (▶Fig. 2 e). Magnifying chromoendoscopy using crystal violet showed a wavy, branched pit, although the staining was not as clear as with other methods, probably owing to adherent mucus (▶Fig. 2 f). Histopathological examination following ileocecal resection revealed a low-grade appendiceal mucinous neoplasm (▶Fig. 3 a, b). Case 2: A 74-year-old man underwent colonoscopy for appendiceal enlargement on computed tomography that showed a similar lesion as described in case 1 (▶Fig. 4 a). Magnifying NBI, chromoendoscopy with indigo carmine, and magnifying chromoendoscopy using crystal violet showed the same findings as in case 1 (▶Fig. 4b, c, d). Following ileocecal resection, histopathology revealed a low-grade appendiceal mucinous neoplasm (▶Fig. 5 a, b) with some adenocarcinoma components in the tail of the appendix. In these cases, low-grade appendiceal mucinous neoplasms were observed as whitish, slightly elevated lesions covered with a mucus cap, and no blood vessels could be identified. The findings were Video 1 Low-grade appendiceal mucinous neoplasms observed on magnifying endoscopy.