University of Edinburgh



Type Ia (spherical) communicating colonic duplication in a dog treated with colectomyCorresponding author and first authorNuria Fernandez LdaVet, MRCVSHospital for Small AnimalsEaster Bush CampusEH25 9RG Roslinnuria.fernandez@ed.ac.uk0131 650 76 50Linda Morrison BVMS,FRCPath, DiplECVP, FHEA, MRCVSTzianna Liuti DVM, Dipl. ECVDI, Pg.CAP, MRCVS, FHEAMairi Frame BVMS , DVR , DipECVDI, MRCVS, FHEADonald Yool BVMS, PhD, DipECVS, CertSAS, MRCVS?A six-month-old Labrador Retriever presented for investigations of a colonic mass identified as an incidental finding during exploratory coeliotomy. Computed tomography identified a lesion in the colon which occupied part of its lumen and shared vascularization with the remainder of the colon. The lesion was suspected to be a colonic duplication. Exploratory coeliotomy and segmental colectomy were performed to excise the colonic lesion. Histopathology from the excised colon confirmed the diagnosis of a colonic duplication. The dog recovered uneventfully and had no complications. To the authors’ knowledge, this is the first report of an asymptomatic, spherical, communicating colonic duplication and the first report to describe segmental colectomy for the management of this condition in veterinary patients. IntroductionGastrointestinal duplications are spherical or tubular congenital lesions lined by gastrointestinal mucosa and well-developed smooth muscle layers which can occur anywhere along the gastrointestinal tract (Gross et al. 1952). Colonic duplication is considered a rare condition in humans and there are only seven single case reports in dogs (Jakowski 1977, Longhofer et al. 1991, Lorinson et al. 1995, Shinozaki et al. 2000, Arthur et al. 2003, Landon et al. 2007, deBattisti et al. 2013) and one in cats (Kramer et al. 2007). In dogs and cats, reported signs include tenesmus, constipation, rectal prolapse, urinary incontinence and stranguria. Diagnosis is often challenging and several diagnostic imaging techniques have been used in dogs and cats including plain and contrast radiography, ultrasonography, colonoscopy and computed tomography. In human medicine, magnetic resonance imaging has also been used (Payne et al. 1995). Four of the seven cases reported in dogs underwent surgical treatment. Treatment involved incision of the intercolonic septum (Shinozaki et al. 2000), excision of the intercolonic septum (deBattisti et al. 2013), local excision of the duplicated portion of intestine in isolation (Arthur et al 2003) and mucosal stripping of the duplicated colon (Landon et al. 2007). In human patients there is a large variability in colonic duplication morphology (Kaur 2004); therefore appropriate treatment recommendations are based on the location, shape and size of the duplication.HistoryA six month old female entire Labrador Retriever was presented for investigation of a colonic mass identified by the referring veterinarian as an incidental finding during a previous exploratory coeliotomy. Initially, the dog was presented to the referring veterinarian with a three-week history of intermittent lethargy, inappetence, abdominal pain and vomiting after witnessed garbage ingestion. Routine haematology and serum biochemistry revealed no abnormalities. Abdominal radiographs showed several gas filled intestinal loops. Gastrointestinal foreign body obstruction was considered likely but coeliotomy failed to identify a foreign body. However, a mass originating within the wall of the ascending colon was identified which appeared to be contiguous with the intestinal lumen. Histopathology of the small intestine biopsies indicated mild plasmacytic and eosinophilic enteritis and cytology collected by fine needle aspirate of the colonic mass was consistent with aspiration of the intestinal lumen. From these findings, dietary indiscretion causing the initial vomiting and an incidental finding of colonic duplication seemed most likely and the dog was referred for management of the colonic mass. On presentation to the referral centre, eleven weeks after the initial surgery, physical examination was unremarkable. Computed tomography (CT) was performed using a 4-slice helical CT unit (Somatom Volume Zoom; Siemens). A small focal area of mineral hyperdensity (7x6x11mm) surrounded by gas was seen in the lumen of the colon close the ileocaecocolic junction in plain CT images. One loop of jejunum was distended but no signs of obstruction were seen. Iopamidol 370 mgI/ml (Niopam, Bracco) was administered intravenously and the lesion demonstrated an enhancing rim and shared vascularisation with the remainder of the colon. The lesion occupied part of the colonic lumen but there was no evidence of obstruction (Figure 1). The differential diagnoses considered were colonic duplication, foreign body, impacted diverticulum, granuloma and neoplasia. Exploratory coeliotomy was performed. Omental adhesions to the distal jejunum were identified, likely secondary to the previous surgery. A 1cm diameter, mass lesion was identified in the mesenteric border of the ascending colon approximately 4 cm aborad from the ileocaecocolic junction. The mass appeared to be a mural lesion, being contiguous with the colonic wall and grossly appearing to comprise healthy intestinal wall. It was firm on palpation and could be felt protruding into the colonic lumen but there was no evidence of obstruction and it occupied less than 50% of the colonic lumen. A segmental colectomy was performed. Margins of 1cm were achieved as more resection would have necessitated resection of the ileocaecocolic junction. An end-to-end anastomosis was performed using a divided, modified simple continuous appositional suture pattern with 3-0 polydioxanone (PDS Plus; Ethicon). Gross examination of the lesion identified that the mass was a generally spherical, discrete area of colon protruding into the main colonic lumen but communicating only through a small stoma (Figure 2). The lesion was impacted with faecal material. The tissues were submitted for histopathological evaluation. Post-operative analgesia was provided using methadone (Comfortan, Eurovet Animal Health) 0.2mg/kg IV q 4h, lidocaine (lidocaine hydrochloride, Hameln Pharmaceuticals) 30 ?g/kg/min CRI and paracetamol (Perfalgan, Bristol-Myers Squibb Pharmaceuticals), 10 mg/kg IV q8h for the first 24h. This was followed by buprenorphine (Buprecare, Animalcare), 0.02 mg/kg IV q 8h. The dog recovered uneventfully and started eating the day after the surgery. A 10-day course of metronidazole (metronidazole, CrescentPharma) 10mg/kg PO q12h was prescribed. Normal defecation was observed 48h after the surgery and the dog was discharged three days post-operatively. Histopathological examination confirmed the diagnosis of a colonic duplication. The cystic lesion was composed of a luminal layer of mucosal epithelium resembling normal colonic mucosa. The mucosa contained prominent goblet cells and mild cryptal hyperplasia. There was a submucosal layer and a muscularis layer which ranged from a single circular layer of muscle to a bilayer of circular and longitudinal muscle. There was an area in the colonic mucosa which showed mucosal attenuation and loss with fibrin debris, consistent with mucosal ulceration. The dog was reported to have fully recovered and to have no apparent adverse effects at the point of the last telephone contact with the owner, 2 months following surgery. DiscussionIn man, colonic duplications are classified into two broad groups (Kottra 1971). Type I duplications are limited to the colon. Type II duplications often involve the entire length of colon and are associated with duplications of the urogenital tract or musculoskeletal system. Type I duplications can be further subdivided into: Type 1a: spherical, Type 1b: tubular, Type 1c: double-barrelled, Type 1d: loop duplications and Type 1 e: multiple duplications. Duplications are additionally classified as either communicating or non-communicating depending on whether or not they have direct communication with the lumen of the rest of the colon. Using this classification system, this case would be classified as having a Type 1a (spherical) communicating colonic duplication. Previously, spherical non-communicating and tubular communicating duplications have been reported in the veterinary literature but, to our knowledge, this is the first case of Type 1a (spherical) communicating duplication reported in the dog. The location of this duplication within the mesenteric border of the intestine is also unusual. Previous veterinary reports describe duplications within the anti-mesenteric border which has facilitated local resection of the lesion whilst leaving the remainder of the colon intact (Arthur 2003). Given the location in this case, local resection carried a high risk of vascular compromise to the remaining colonic wall surrounding the duplication and complete resection of the affected portion of colon was considered to be more appropriate. Similarly, although resection of the intraluminal septum separating the duplication from the colonic lumen would be possible, the location on the mesenteric surface of the intestine did not lend itself to this approach. The choice of imaging study in this case was influenced by the prior investigations performed by the referring veterinarian which had identified the location and size of the mass. In this case, abdominal ultrasound may have been valuable pre-operatively but CT with intravenous contrast was chosen in preference in order to more accurately determine the major blood supply of the lesion and the relationship of the lesion to adjacent structures. This allowed more effective surgical planning. CT also offers the advantage of comprehensive screening of the entire abdomen, spine and perineum for concurrent congenital anomalies which are occasionally reported in man. Colonoscopy could have been performed to assess the connection of the lesion with the colonic lumen, however the ostium may have not been identified due to its small size and the presence of colonic contents and the intraluminal appearance of the area of duplication could have been difficult to interpret. Regardless of the nature of imaging study performed, preoperative imaging to help establish, size, location and extent of the lesion and any associated gastrointestinal obstruction is recommended. Colonic duplication in this dog was asymptomatic. In a review by Puligandla et al (2003), 21 of 73 (28.8%) of gastrointestinal duplications in people were asymptomatic. However, in man, colonic duplication has been associated with development of major complications such as spontaneous perforation (Piolat et al 2005), abscess formation (Limas et al 2009), intussusception (Reiser-Erkan et al. 2010), colonic torsion (O?uzkurt et al. 2004) and hydronephrosis (Ravitch 1953). Neoplastic transformation has also been reported (Orr and Edwards 1975, Hickey and Corson 1981). With the advent of prenatal diagnosis and early surgical management of gastrointestinal duplications, complications such as volvulus and intussusception have been significantly decreased (Puligandla et al. 2003). The current recommendation in man is surgical treatment of all gastrointestinal duplications, even if they are asymptomatic, in order to prevent the development of complications. Colorectal duplications are benign lesions and, for this reason, surgical excision should be not be radical. However, because of the potential for complications and neoplastic transformation, complete excision, as performed in this case, should be performed when possible (Holcomb et al. 1989). This is the first report describing an asymptomatic type Ia (spherical) communicating colonic duplication located in the mesenteric border and the first report to describe segmental colectomy for the management of this condition in veterinary patients. In conclusion, surgical excision of colonic duplications should always be considered not only as a symptomatic treatment but also as a prophylactic treatment to prevent life-threatening complications. Figure 1. Transverse CT images pre (A) and post contrast (B) at the level of the ileocecocolic junction and colonic duplication. White arrow showing the mineralization (A) and the rim enhancement surrounding the colonic duplication (B). Key: L= Left; R= Right. Sagittal CT multiplanar post contrast image (C) at the level of the ileocecocolic junction and colonic duplication. White arrow showing the rim enhancement surrounding the colonic duplication. Key: Cr= Cranial; Cd= CaudalFigure 2. Resected portion of colon (A). Mass protruding into colonic lumen. Haemostat showing stoma in the centre of the mass. Formalin fixed resected portion of colon (B). Visible spherical shape and stoma in the centre of the mass. ReferencesArthur, E. G., Fox, D. B., Essman, S. C., et al. (2003) Surgical treatment of noncommunicating duplication of the colon in a dog. Journal of American Veterinary Medical Association 223, 210-214.DeBattisti, A., Harran, N., Chanoit, G. and Warren-Smith, C. (2013) Use of negative contrast computed tomography for diagnosis of a colonic duplication in a dog. Journal of Small Animal Practice 54, 547-550Gross, R.E., Holcomb, G. W. & Farber, S. (1952) Duplications of the alimentary tract. Pediatrics 9, 449-468Hickey, W.F., Corson, J. M. (1981) Squamous cell carcinoma arising in a duplication of the colon case report and literature review of squamous cell carcinoma of the colon and of malignancy complicating colonic duplication. Cancer 47, 602-609Holcomb, G. W., Gheissari, A., O?Neill, J.A. 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