case_images: PMC9035920_01
case_images: Endoscopic findings of the lesion. a The lesion shows a SET. A bridging hold was observed on the smooth surface of the lesion under white light; the lesion has a solid appearance. b Image after indigo carmine spraying. No ulcer or erosion is observed on the lesion surface. c No irregular vessels are observed on the lesion surface in narrow-band imaging. d EUS indicated that this SET might be located at the second or third layers but did not provide additional information due to poor endoscopic manipulation and deep echo attenuation.
case_images: crg-0016-0216-g01.jpg
case_images: PMC9035920_01_crg-0016-0216-g01.jpg
case_images: F1
case_images: He underwent endoscopy in our hospital, which showed a 10 mm SET, without ulceration or cushion sign (Fig. 1). Furthermore, EUS via the water-filling method using an ultrasound probe demonstrated that this lesion might be derived from the second or third layers; however, it did not provide additional information for the differential diagnosis of SET due to the insufficient manipulation of the scope (Fig. 1d).
case_images: Endoscopic images during ESD. a A loop was formed in the transverse colon, and the scope manipulation was poor. b A single-use splinting tube was placed before the ESD procedure. c Poor visualization of the cutting area makes colorectal ESD difficult. d Mild fibrosis is identified during the dissection of the submucosa. e The edge of the exfoliated mucosa was attached with the spring S-O clip, which makes cutting submucosal area more visible. f Immediately after ESD, the resected specimen is measured and is found to be 25 x 20 mm.
case_images: crg-0016-0216-g02.jpg
case_images: PMC9035920_01_crg-0016-0216-g02.jpg
case_images: F2
case_images: Ltd, Tokyo, Japan) for stable endoscopic manipulation (Fig. 2a, b). Because fibrosis was observed in the submucosa (Fig. 2c, d), the spring S-O clip traction method (TC1H05, Zeon Medical Tokyo, Tokyo, Japan) facilitated submucosal dissection (Fig. 2e). Finally, en bloc resection was achieved in 44 min without any adverse events (Fig. 2f).
case_images: Histological findings of the resected specimens. a The lesion is 8 x 7 mm. It is located in the submucosa, and the surface is covered with non-neoplastic mucosa. b Atypical cells with round-to-oval nuclei and acidophilic vesicles are observed (HE staining. x400 magnification). c Immunohistochemistry reveals strong expression of S-100 protein in the lesion. d Low expression of Ki-67 labeling (x200 magnification).
case_images: crg-0016-0216-g03.jpg
case_images: PMC9035920_01_crg-0016-0216-g03.jpg
case_images: F3
case_images: Atypical cells with round-to-oval nuclei and acidophilic vesicles were observed on HE staining (Fig. 3a, b). Moreover, immunohistochemical staining for S-100 protein was strongly positive, and the Ki-67 labeling index was 5% (Fig. 3c, d).