Colonic muco-submucosal elongated polyp: diagnosis with endoscopic ultrasound

A case of giant enteric muco-submucosal elongated polyp detected by melena

A 78-year-old woman was admitted for examination and treatment of melena. Although upper and lower gastrointestinal endoscopy and abdominal computed tomography showed no bleeding lesions, oral double-balloon endoscopy revealed a long, slender polyp covered with normal mucosa and accompanied with erosions in the proximal jejunum. Surgical resection was successful. Histopathologically, the polyp was 125 mm in length and composed of edematous mucosa with dilated blood vessels. The growth was diagnosed as a rare enteric muco-submucosal elongated polyp. Her melena improved postoperatively.

A Case of Giant Colonic Muco-submucosal Elongated Polyps Associated with Intussusception

Colonic muco-submucosal elongated polyp (CMSEP), a newly categorized non-neoplastic colorectal polyp, is a pedunculated and elongated polyp composed of normal mucosal and submucosal layers without any proper muscle layer. We herein report a giant variant of CMSEP associated with intussusception in the rectosigmoid colon, with a review of the literature. A 48-year-old woman underwent a laparoscopic low anterior resection due to multiple large submucosal polypoid masses associated with intussusception. Grossly, the colonic masses were multiple pedunculated polyps with a long stalk and branches ranging in size from a few millimeters to 14.0 cm in length. Microscopically, there was no evidence of hyperplasia, atypia, or active inflammation in the mucosa. The submucosal layers were composed of edematous and fibrotic stroma with fat tissue, dilated vessels, and lymphoid follicles.

Colonic mucosubmucosal elongated polyp: report of a series of 14 cases and review of the literature

AIMS

Most colorectal polyps can be reliably assigned to one of the known polyp categories, but a subset of polyps named colonic mucosubmucosal elongated polyps (CMSEPs) do not fall into any of these categories. First described in the Japanese literature, CMSEPs seem to be under-recognized in the Western literature. The aims of this study were to describe the clinicopathological features of 14 CMSEPs, discuss potential pathogenetic mechanisms, and increase awareness of this entity among pathologists.

METHODS AND RESULTS

Fourteen pedunculated colorectal polyps that met the histopathological criteria for CMSEP (as described by Matake et al. and Alizart et al.) were assessed (12 males and two females; mean age 59.7 years). Five polyps were located in the sigmoid colon, four in the rectum, two in the descending colon, and three in the colon not otherwise specified. Nine of 14 polyps were discovered incidentally: two of nine on routine screening colonoscopy, two of nine on surveillance colonoscopy for inflammatory bowel disease (IBD), and five of nine upon surgical intervention for carcinoma or IBD. None coexisted with diverticular disease. The polyps were long and slender, varied from 5 to 30 mm in length (mean 15.9 mm), and showed a normal-looking colonic mucosal layer and underlying loose submucosa with thick-walled and congested blood vessels and lymphatics.

CONCLUSIONS

CMSEPs show subtle but distinctive pathological features, and occur in normal and diseased colons. Pathologists need to be aware of this entity, to avoid confusion with other more commonly encountered colorectal polyps. With increasing colon cancer screening programmes and surveillance colonoscopy, it is likely that CMSEPs will be encountered more often.

Muco-submucosal elongated polyps of the gastrointestinal tract: A case series and a review of the literature

We present three cases of gastrointestinal muco-submucosal elongated polyps, two located in the duodenum and one in the descending colon. All three cases had a characteristic, “worm-like” endoscopic appearance and were lined by unremarkable mucosa. The vascular component was located in the submucosa and was composed of a mixture of variably dilated blood vessels (capillaries and veins) and lymphatics. The duodenal polyps displayed lipomatous metaplasia of the submucosal stroma. The dual vascular phenotype of the vascular component was confirmed by immunohistochemistry with D2-40 and CD31.

A case of nonpolypoid cancer arising from colonic muco-submucosal elongated polyp

A colonic muco-submucosal elongated polyp (CMSEP) was identified at colonoscopy in a 53-year-old male patient with lower gastrointestinal bleeding. Non-polypoid depressed type of early cancer was noted at the tip of the colonic polyp. The CMSEP is very rare and incidentally found in most cases. Moreover, its association with colonic neoplasia is extremely rare. To our knowledge, this is the second case report of CMSEP associated with a cancerous transformation.

Colonic mucosubmucosal elongated polyp: a clinicopathologic study of 13 cases and review of the literature

Colonic mucosubmucosal elongated polyp (CMSEP) is a distinctive non-neoplastic colorectal polyp characterized by pedunculated, elongated shape and is composed mainly of expanded submucosa with a normal mucosal lining. Only a small number of these polyps have been reported, exclusively from Japan. We report the clinicopathologic characteristics of 13 CMSEPs occurring in 11 patients, mostly from European ancestry. Ten of these polyps were resected during colonoscopy, and 3 were diagnosed in a patient who underwent sigmoid resection for diverticular disease. Among patients who had undergone a colonoscopy, 4 had altered bowel habit, and 1 suffered from abdominal discomfort; the other 5 patients had routine screening colonoscopy. Eight polyps were located in the sigmoid colon, 3 in the right colon, 1 in the rectosigmoid junction, and 1 in the descending colon. Polyp size ranged from 10 to 150 mm. Histologically, CMSEPs were characterized by unremarkable large bowel mucosa and submucosal stalk containing dilated thick-walled veins running parallel to the long axis of the polyp. Mucosal inflammation or fibromuscular proliferation characteristic of mucosal prolapse was absent. The pathogenesis of CMSEP may involve mechanical traction of the mucosa and the superficial submucosa during peristalsis in a fragile area of the colon. Despite the occasional large size, CMSEP is a benign lesion seldom leading to clinical complications.