Case Report

International Journal of Anatomical Variations (2013) 6: 145–148eISSN 1308-4038

Mesenteric Meckel’s diverticulum: a real variant

IntroductionA Meckel’s diverticulum (MD) is the most common congenital anomaly of the gastro-intestinal tract, and can present diagnostic and surgical challenges. Arising from failure of the omphalomesenteric duct to close properly, MD can occur in up to 2% of the population and can manifest as obscure gastrointestinal bleeding, Meckel’s diverticulitis, obstruction, and intussusception [1]. While most MDs present in childhood, adult patients are also at risk for complications, though these tend to decrease with increasing age [2, 3]. Several characteristics that facilitate identification of a Meckel’s diverticulum include location two feet proximal to the ileocecal valve, the presence of an independent vessel supplying the structure, five layers of small intestine, and ectopic mucosa of either gastric, pancreatic or another origin other than small intestine in a majority of specimens [4]. There are very few cases of mesenteric-sided MD reported in surgical literature (Table 1), and several authors have suggested that what some call a mesenteric-sided MD may in fact be an intestinal duplication cyst [4–9]. This study reports a case of what the authors believe to be a mesenteric MD and reviews the literature concerning identification and appropriate treatment of a MD in the minimally invasive era.

Case ReportA 35-year-old otherwise healthy gentleman noticed a small quantity of maroon colored stools for one week, worsening over time. He eventually reported to a local emergency department with symptoms of orthostasis and required transfusion of 2 units of packed red blood cells. Extensive gastroenterologic workup included a video-capsule endoscopy which identified blood in the ileum. A subsequent double-balloon enteroscopy indicated friable ileal mucosa with contact bleeding reportedly 120 cm from the ileocecal valve. A tattoo was placed at the point of interest. A Meckel’s scan was then performed at the outside facility and was negative.No additional intervention was undertaken by the patient until two weeks prior to his presentation to our clinic, which was one year after his first episode. Upon further questioning the patient had used NSAIDs prior to first episode of bleeding and aspirin prior to second episode. Workup at our institution included computed tomography (CT) scanning with enterography, as well as a review of the patient’s outside capsule endoscopy. CT enterography revealed a “tubular outpouching” adjacent to the distal ileum and ascending colon that was considered consistent with the expected appearance of a Meckel’s diverticulum (Figure 1). In light of

Susanne G. CARPENTER [1]

Ann E. McCULLOUGH [2]

Shabana PASHA [3]

Kristi L. HAROLD [1]

Departments of Surgery [1], Pathology [2], Gastroenterology [3], Mayo Clinic, Phoenix, AZ, USA.

Kristi Harold, MD Mayo Clinic Arizona 5777 E. Mayo Blvd. Phoenix, AZ 85054 USA. +1 (480) 342-2849 harold.kristi@mayo.edu

Received July 4th, 2012; accepted September 30th, 2012

AbstractA Meckel’s diverticulum is the most common congenital abnormality of the gastrointestinal tract and can present a variety of diagnostic and surgical challenges. A longstanding surgical dictum is that a Meckel’s diverticulum must be anti-mesenteric. This study reports the case of an adult male who presented with an obscure gastrointestinal bleed and was ultimately found to have a Meckel’s diverticulum on the mesenteric intestinal border which was resected laparoscopically. Diagnostic characteristics that facilitate identification of a Meckel’s diverticulum along with reported deviations from these characteristics are reviewed in this study.

© Int J Anat Var (IJAV). 2013; 6: 145–148.

Key words [Meckel’s diverticulum] [mesenteric sided Meckel’s diverticulum] [Meckel’s diverticulitis][congenital gastrointestinal anomalies]

Published online September 11th, 2013 © http://www.ijav.org

146 Carpenter et al.

the enterography results, a Meckel’s scan was repeated and revealed tracer uptake in the right lower quadrant consistent with a Meckel’s diverticulum (Figure 2). With this information, the patient was taken to the operating room where an exploratory laparoscopy with small bowel resection and side-to-side anastomosis was performed. The initial dissection was performed using three 5 mm trochars placed along the lateral left abdominal wall. Upon examination of the small intestine, a diverticulum was noted at approximately 60 cm from the ileocecal junction. However, this was found along the mesenteric border of the ileum (Figure 3). The tattoo indicating the furthest extent of the previous outside institution double balloon enteroscopy was noted to be at least 20 cm distal to the diverticulum (Figure 4). This area was not resected. One of three 5 mm trocars was upsized to a 12 mm in order to permit use of an Endo-GIA stapler (Covidien) which was employed for the transaction of the small bowel and mesentery surrounding the diverticulum (Figure 5). The diverticulum was sent to pathology where gross examination as well as frozen and permanent sections revealed the presence of ectopic gastric mucosa (Figure 6a & b). Final pathology revealed a 7 cm x 2.5 cm pouch-like diverticulum containing a 3.5 cm area of mucosa with a granular appearance as opposed to the tan folds of the surrounding ileum. Microscopically, hematoxylin and eosin staining revealed erosion adjacent to reactive oxyntic gastric type mucosa.

Figure 1. CT enterography demonstrating intestinal outpouching consistent with Meckel’s diverticulum.

Table 1. Cases of mesenteric-sided MD reported in surgical literature.

Author & year Presentation Procedure performed Distance from ICV OR findings Path findings

Segal et al. 2004, [7] 19-year-old, M,

acute abdominal pain

Low transverse RLQ incision, small

bowel resection, WLE mesentery

63.5 cmAdenopathy, forshortened

mesentery

Gastric mucosa w/ metaplasia

Manukyan et al., 2009, [9]

15-year-old, F, acute abdominal

pain

Standard laparotomy Mesenteric MD

Pancreatic, gastric mucosa with

chronic ulcerationSarioglu-Buke et al., 2008, [5] 7-month-old, M

Laparotomy, small bowel resection and anastomosis

40 cm

Mesenteric lymphadenopathy,

2 cm base, wide ileal connection

Fibrin accumulation, gastric mucosa

Seitun et al., 2011, [6] 65-year-old, F, RLQ

abdominal pain

Lower midline incision, stapled

transverse diverticulectomy

40 cm Mesenteric abscess RLQ, inflamed MD

Heterotopic gastric mucosa w/

perforation

Carpenter et al., 2013

35-year-old, M, obscure GI bleed

Laparoscopic small bowel resection 60 cm Mesenteric MD Gastric mucosa

M: male; F: female; WLE: wide local excision; RLQ: right lower quadrant; ICV: ileocecal valve; OR: operating room; Path: pathology

147Mesenteric Meckel’s diverticulum

DiscussionSeveral other authors have reported MD presenting on the mesenteric border. Some argue this can only be an intestinal duplication cyst, but a case reported by Kurzbart and colleagues suggests otherwise as contrast was administered to a newborn infant of 28 weeks gestation via a fourth lumen in the transected umbilical cord [5, 7, 8]. Contrast filled the small bowel upon injection. At 3 months of age, the infant underwent an umbilical hernia repair. No residual omphalomesenteric structures were present, however a MD was found 40 cm from the ileocecal junction but adherent to the mesentery [8]. Several explanations for the reported mesenteric locations have been offered including that a shortened vitelline artery could form a mesodiverticular band from the ileal mesentery to the tip of the diverticulum which would then divert the diverticulum away from the antimesenteric border during elongation and fetal growth

Figure 4. Tattoo (arrow) of previous double-balloon endoscopy.

Figure 5. Resection of small bowel and mesentery surrounding diverticulum using Endo GIA stapler (Covidien). (Arrow: mesenteric staple line)

Figure 2. Meckel’s scan with uptake in right lower quadrant.

Figure 3. Laparoscopic view identifying Meckel’s diverticulum (arrow) embedded in mesentery.

[5]. Another explanation is that the vitelline duct would simply adhere to the ileal mesentery [1]. Several other authors presenting cases of mesenteric-sided MD have openly pondered if they may have been dealing with an intestinal duplication cyst rather than a MD [4]. This begs the question of how one might differentiate the two. It seems that the absence of a distinct communication of a structure with adjacent intestinal lumen would favor intestinal cyst or duplication [7]. Our patient had a clear connection between lumens of his MD and the ileum. Another possible area of distinction is with ectopic gastric mucosa, which our patient demonstrated. However, ectopic gastric or pancreatic mucosa can be found in both MD (approximately 55%) and intestinal duplication cysts (approximately 16-39%) [1, 7, 10].

148 Carpenter et al.

Figure 6. a) Opened diverticulum. Gastric fundic type mucosa is pink granular mucosa on right; small intestinal mucosa is tan mucosa with folds on left. b) Diverticular mucosa, hematoxylin and eosin, x40. Villi from small intestinal mucosa (thin arrow), erosion at 6 o’clock (short arrow), reactive oxyntic gastric type mucosa (thick arrow)

b

GFM

a

SIM

Some authors have asserted that the presence of a vitelline artery or a clear independent blood supply to a diverticulum is definitive evidence of MD whereas intestinal duplications share blood supply with the surrounding intestine [7, 11]. However, Kusumoto and colleagues have indicated that a distinct vitelline artery could be identified in only 10% of 776 patients with MD [12]. In the case here presented, a

distinct blood supply was identified on CT scan, but attempts were not made to delineate this vessel intraoperatively or pathologically. In brief, we are left with the conclusions of previous authors that while the behavior and presentation of the lesion were more consistent with MD, we cannot definitively rule out a simple intestinal diverticulum or duplication cyst.

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