Long pedunculated colonic polyp composed of mucosa and submucosa: proposal of a new entity, colonic muco-submucosal elongated polyp

Multiple enteric muco-submucosal elongated polyps causing intussusception

A 20-year-old woman presented to our hospital with abdominal pain. Abdominal computed tomography revealed multiple masses in the upper jejunum, which were suspected as lipomas. Partial resection of the small intestine, including the masses, was performed on the same day due to intussusception secondary to the masses. Pathological examination revealed that the masses consisted of mucosa and edematous submucosa with multiple dilated blood vessels and lymphatic ducts without muscularis propria. The masses were diagnosed as multiple muco-submucosal elongated polyps (MSEP), a type of non-neoplastic polyp. MSEP was originally named colonic MSEP, but with the development of endoscopic techniques and imaging tests, similar polyps have been reported to occur not only in the colon but also in the entire intestinal tract. In this case, multiple MSEPs in the upper jejunum caused intussusception. As reported cases of multiple lesions causing intussusception are few, our case may help to clarify the pathogenesis of this disease.

A case of colonic muco-submucosal elongated polyp (CMSEP) misdiagnosed as a inverted colonic diverticulum (ICD)

CMSEP is a large intestine polyp with a long and broad stalk and a "worm-like" appearance which is covered by normal mucosa. The submucosal layer consists of edematous and fibrotic interstitium, adipose tissue, dilated blood vessels, and lymphatic follicles[1]. Endoscopic magnification of the mucosal surface showed a uniform honeycomb pattern of regular blood vessels, with soft and deformable "folds" and "gyrus" at the top. The exact pathogenesis of CMSEP is still unclear.

Risk factors of unintentional piecemeal resection in endoscopic mucosal resection for colorectal polyps ≥ 10 mm

This study aimed to investigate the lesion and endoscopist factors associated with unintentional endoscopic piecemeal mucosal resection (uniEPMR) of colorectal lesions ≥ 10 mm. uniEPMR was defined from the medical record as anything other than a preoperatively planned EPMR. Factors leading to uniEPMR were identified by retrospective univariate and multivariate analyses of lesions ≥ 10 mm (adenoma including sessile serrated lesion and carcinoma) that were treated with endoscopic mucosal resection (EMR) at three hospitals. Additionally, a questionnaire survey was conducted to determine the number of cases treated by each endoscopist. A learning curve (LC) was created for each lesion size based on the number of experienced cases and the percentage of uniEPMR. Of 2557 lesions, 327 lesions underwent uniEPMR. The recurrence rate of uniEPMR was 2.8%. Multivariate analysis showed that lesion diameter ≥ 30 mm (odds ratio 11.83, 95% confidence interval 6.80-20.60, p < 0.0001) was the most associated risk factor leading to uniEPMR. In the LC analysis, the proportion of uniEPMR decreased for lesion sizes of 10-19 mm until 160 cases. The proportion of uniEPMR decreased with the number of experienced cases in the 20-29 mm range, while there was no correlation between the number of experienced cases and the proportion of uniEPMR ≥ 30 mm. These results suggest that 160 cases seem to be the minimum number of cases needed to be proficient in en bloc EMR. Additionally, while lesion sizes of 10-29 mm are considered suitable for EMR, lesion sizes ≥ 30 mm are not applicable for en bloc EMR from the perspective of both lesion and endoscopist factors.

A feces‐filled non‐inverted ileal pseudodiverticulum presenting as a pedunculated polyp successfully treated by traction‐assisted endoscopic submucosal dissection

A 68‐year‐old man was referred to our hospital for endoscopic treatment of colon polyps detected at a local clinic. Colonoscopy revealed not only classical adenomatous polyps in the transverse and sigmoid colon but also an atypical pedunculated polyp in the terminal ileum with the head of the lesion moving back and forth through the ileocecal valve. Based on the endoscopic findings, the pedunculated polyp was diagnosed as a non‐epithelial tumor of the ileum. However, traction‐assisted endoscopic submucosal dissection was performed because of the high risk of intestinal intussusception or obstruction. Histopathological analysis of the resected specimen revealed that the pedunculated polyp was a non‐inverted ileal pseudodiverticulum filled with feces. We report the first case of a feces‐filled non‐inverted pseudodiverticulum presenting as a pedunculated polyp successfully treated by traction‐assisted endoscopic submucosal dissection.

Jejunal intussusception and perforation due to enteric muco-submucosal elongated polyp: a case report and literature review

BACKGROUND

A muco-submucosal elongated polyp is a non-neoplastic growth composed of mucosa and submucosa. Although muco-submucosal elongated polyps are commonly reported in the large intestine, they are rare in the small intestine, in which they are called enteric muco-submucosal elongated polyps. We herein present a case of jejunal intussusception and perforation due to an enteric muco-submucosal elongated polyp.

CASE PRESENTATION

A 46-year-old woman presented with abdominal pain and vomiting. Computed tomography revealed jejunal intussusception, which was reduced via a nasointestinal ileus tube. Oral double-balloon endoscopy showed an elongated polyp in the proximal jejunum. The patient refused surgical resection and thus, the polyp was monitored. Six months later, the patient was readmitted with the recurrence of jejunal intussusception and underwent emergency surgery. Intraoperative findings revealed an intussuscepted bowel with an elongated polyp and multiple perforations in the proximal jejunum. We resected approximately 90 cm of the bowel, including the intussuscepted segment and perforated sites. The pedunculated polyp, which was 60 mm in length, was located on the oral side of the resected specimen. Histopathologically, the polyp was covered by normal mucosa and the submucosa consisted of edematous loose connective tissue. The histopathological diagnosis confirmed an enteric muco-submucosal elongated polyp.

CONCLUSIONS

Symptomatic patients with enteric muco-submucosal elongated polyps may be at risk of complications, as observed in the present case, and need to undergo timely resection.

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.

Colonic Mucosubmucosal Elongated Polyp in the Sigmoid Colon on Surveillance Colonoscopy

Colonic mucosubmucosal elongated polyp (CMSEP) is a newly designated colorectal polyp. It has unique endoscopic features of a worm- or drumstick-shaped appearance. Histologically, it is composed of normal colonic mucosa and expanded submucosa with a prominent vascular component and no significant inflammation. CMSEP is usually detected incidentally on screening colonoscopy or colonoscopy for other causes. Differential diagnoses that need to be considered include mucosal prolapse syndrome, filiform polyposis, hamartomatous polyp, colon leiomyoma, inverted diverticulum, and residual stalk of a pedunculated adenoma. We present a case of CMSEP on surveillance colonoscopy and literature review.

Two Cases of Leiomyoma in the Colon Masquerading as Other Types of Colonic Pedunculated Polyps

We describe two cases of leiomyoma in the colon that were diagnosed histologically after endoscopic resection. The first case was a 79-year-old Japanese woman who presented with a pedunculated polyp of 14 mm length at the splenic flexure. Preoperative diagnosis suggested a colonic mucosubmucosal elongated polyp. The second case was a 29-year-old Japanese woman who presented with a pedunculated polyp of 40 mm length at the hepatic flexure and had an ulcer on top of the polyp. Preoperative diagnosis suggested an inflammatory fibroid polyp. A pathological diagnosis of colonic leiomyoma was made after endoscopic resection in both cases. Both tumors were confirmed to originate, not from the proper muscle layer, but from the muscularis mucosae. These cases underscore that although colonic involvement is infrequent, leiomyomas can display pedunculated morphology in the colon rather than the typical gross appearance of gastrointestinal submucosal tumors seen with sessile morphology.

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.

Familial Occurrence of Enteric Muco-Submucosal Elongated Polyp

We report 2 cases of enteric muco-submucosal elongated polyps (EMSEPs) that presented with gastrointestinal bleeding. The 2 patients are siblings. They both had a history of percutaneous coronary intervention for coronary artery disease and were on dual antiplatelet therapy. They underwent endoscopic resection of the polyps, which displayed identical endoscopic and histological features compatible with EMSEP. This is the first report of familial occurrence of EMSEP, suggesting possible genetic involvement. It is also important to note that the use of antiplatelet agents appears to be a predisposing factor for gastrointestinal bleeding from EMSEP.

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.

Colonic muco-submucosal elongated polyp: diagnosis with endoscopic ultrasound

Colonic muco-submucosal elongated polyp is a new clinical entity first reported in 1998. The purpose of this report is to determine the value of endoscopic ultrasound in the diagnosis of this condition. We reviewed the endosonographic and histological findings of seven colonic muco-submucosal elongated polyps that were removed completely by endoscopic resection or surgery. The lesions appeared as pedunculated submucosal tumours, measuring 1-4 cm in maximal diameter. Endosonographically, all lesions consisted of mucosal and submucosal layers, and microcystic components were found in the submucosal layer. There were no echogenic masses or muscularis propria within the polyps. These endosonographic features corresponded to histological findings of this type of polyp which was covered with normal mucosa and composed of submucosal layer alone. The submucosal layer consisted of oedematous, loose, connective tissue and/or fibrous tissue, accompanied by dilated blood vessels and lymphatics. Endoscopic ultrasound enabled differentiation of colonic muco-submucosal elongated polyp from other submucosal lesions.