An Unusual Case of a Perforated Meckel's Diverticulum

Background Meckel's diverticulum, the most common congenital anomaly of the gastrointestinal tract, typically presents in children with gastrointestinal bleeding. Case Presentation. An 11-year-old Caucasian male presented with a 6 week history of abdominal pain, vomiting, and diarrhea. He was found to have iron deficiency anemia, markedly elevated serum and fecal inflammatory markers, and imaging showing a contained bowel perforation. He was evaluated for infectious etiologies and later underwent extensive testing for inflammatory bowel disease. Ultimately, he was found to have a Meckel's diverticulum, which was successfully resected and led to resolution of his gastrointestinal complaints. Conclusions This case report highlights one of the more rare presentations in children, which is intestinal perforation. Symptoms of a Meckel's diverticulum can overlap with those of inflammatory bowel disease, as demonstrated by our patient. Clinicians should be familiar with criteria to establish diagnosis of inflammatory bowel disease, and if diagnosis isn't fully supported by testing, they should expand the differential and consider Meckel's diverticulum.


Introduction
Meckel's diverticulum is a congenital diverticulum on the ileum caused by incomplete atrophy of the omphalomesenteric duct [1]. It is the most common congenital anomaly of the gastrointestinal tract. Meckel's diverticulum occurs in 2% of the population, and although most are clinically silent, those who become symptomatic often do so before 2 years of age. Based on one of the largest databases for children with symptomatic Meckel's diverticulum, only 2% of children become symptomatic. Of those with symptoms, 60% of children present with obstruction, 35% with gastrointestinal bleeding, and 8% with infammation [1,2]. Chronic irondefciency anemia has also been reported as an early manifestation of Meckel's diverticulum [3]. Painless gastrointestinal hemorrhage is the consequence of acid originating from a patch of ectopic gastric tissue in the Meckel's, which causes peptic ulcer formation within the diverticulum or disruption of the downstream intestinal mucosa. Infammation occurs in the diverticulum itself, and perforation, a rare complication, can occur secondary to diverticulitis or ulcer within the Meckel's [1,4].
Infammatory bowel disease (IBD) is a chronic immunemediated condition of the gastrointestinal tract, with a rising incidence within the last 10 years. Approximately 25% of patients with IBD are diagnosed before twenty years of age [5]. IBD can present with a variety of symptoms such as abdominal pain, diarrhea, rectal bleeding, weightloss, or growth failure. Patients can also present with surgical emergencies including peritonitis, small bowel obstruction, appendicitis, or abscess. If an otherwise healthy child presents with an acute intestinal surgical emergency accompanied by poor growth and signs of chronicity, there is always a concern for infammatory bowel disease, primarily Crohn's disease [5].
Te authors present a case of an 11-year-old male with initial clinical picture of IBD, subsequently found to have perforated Meckel's diverticulum with abscess formation. Tis case is unique because it is one of just a few cases of a perforated Meckel's in children. Trough this case, clinicians can learn about this rare complication of Meckel's, and how many symptoms and fndings on the clinical workup can overlap with Crohn's disease.

Case Presentation
An 11-year-old male with no past medical history, travel history, or family medical history presented with a 6-week history of gradually worsening periumbilical pain and two weeks of nonbilious vomiting, nonbloody diarrhea, and fever. History was negative for extra-intestinal symptoms such as joint pain or swelling, oral ulcers, eye pain, or skin rash. His physical exam was signifcant for difuse abdominal tenderness but guarding or distention. Computerized tomography (CT) scan of abdomen and pelvis showed signs of infammation in the ascending and transverse colon, and a contained bowel perforation ( Figure 1). Laboratory investigation was signifcant for white blood cell count of 6 thou/cu mm (normal 4.5-13.5 thou/cu mm), hemoglobin of 9.9 g/dL (normal 11.5-15.5 g/dL), C-reactive protein of 221 mg/L (normal 0-5 mg/L), albumin of 2.5 g/dL (normal 3.5-5.2 g/dL), ferritin of 9 ng/mL (normal 24-336 ng/mL), and negative PCR stool studies for viral, bacterial, and parasitic infection. Fecal calprotectin was signifcantly elevated, at >1250 μg/g (normal 0-50 μg/g). We suspected a diagnosis of IBD versus a prior severe infectious colitis that was not detectable by stool PCR testing. Because the patient did not have free air in the abdomen or peritoneal signs, laparotomy was deferred and the patient received 14 days of broad-spectrum antibiotics, which lead to resolution of abdominal pain, vomiting, diarrhea, and fever.
After completing antibiotics, esophagogastroduodenoscopy (EGD) and colonoscopy revealed grossly normal intestinal mucosa, with biopsy fndings of focal active ileitis and colitis, nonspecifc and insufcient for diagnosis of IBD. Intestinal tuberculosis was considered, but QuantiFERON-TB test was negative, and imaging and histology did not support this diagnosis. 4th-generation IBD diagnostic test (commercial in US PROMETHEUS) which combines serologic, genetic, and infammation markers including 9 serological markers: ASCA IgA, ASCA IgG, and proprietary markers anti-Fla-X, anti-A4-Fla2, anti-CBir1, anti-OMPC, and DNAse-sensitive pANCA that helps identify patients with IBD was negative for IBD, and repeat fecal calprotectin, serum infammatory markers, complete blood count, and albumin had all normalized, without any treatment for IBD. Te patient then developed daily bloody stools and was started on infiximab based on symptoms and ileal infammation on MRE, though need for further testing with wireless capsule endoscopy was being planned to further solidify diagnosis. Several weeks after initiating treatment for IBD, the patient presented with worsening of abdominal pain and fever. A CT scan revealed signs suggestive of a 7.6 × 4.3 × 7 cm phlegmon adjacent to the bowel in the right lower abdomen.
With work-up not defnitive for IBD, other causes for intra-abdominal abscess were considered, and concern for Meckel's diverticulum was raised. A technetium 99 m scan was obtained, and fndings were consistent with Meckel's diverticulum ( Figure 3). Nine months after this patient's onset of symptoms, laparoscopic exploration was performed, and a Meckel's diverticulum was identifed. At the time of surgery, there was no abscess and no sign of perforation. Te diverticulum was covered by a rind of infammatory tissue, and the location of this infammatory mass was concordant with the location of the phlegmon on the aforementioned CT scan. Another fnding at the time of surgery was the presence of adhesions. Resection diverticulectomy with side-to-side anastomosis was performed. Histology confrmed this diagnosis. Patient's abdominal pain and hematochezia resolved after surgery. Te patient was followed for 15 months after surgery and has remained asymptomatic since then.

Discussion
A Meckel's diverticulum simulates the shape of a duplication cyst or blind pouch separated from the ileum when observed on abdominal ultrasound and CT. Meckel's might be diffcult to distinguish from the adjoining small bowel loops on imaging, making diagnosis by these imaging modalities more challenging. Pertechnetate scintigraphy, with H2 receptor blocker given before the scan to improve accuracy,   Case Reports in Pediatrics provides a diagnostic sensitivity of 94%-100% and a specifcity of up to 97-100% in diagnosing heterotopic gastric mucosa within a Meckel's diverticulum in children although it is operator dependent [6]. Te treatment of choice is surgical resection [2]. Our case is that of a child with subacute nonbloody diarrhea and initial radiologic fndings of severe infectious colitis versus infammatory bowel disease in the right hemiabdomen, with contained perforation. Such fndings plus clinical symptoms and initial laboratory evaluation (iron defciency with anemia, hypoalbuminemia, and elevated serum and fecal infammatory markers) made us suspect a diagnosis of IBD initially, since up to 28% of patients with newly diagnosed CD can present with penetrating (intraabdominal abscesses or fstula) or structuring disease; however, the incidence of intra-abdominal abscesses alone is not known [5]. Tough biopsy results with minimal focal active ileitis and colitis were nonspecifc for IBD, we entertained the possibility that he could have early evolving IBD. Te patient's MRE raised suspicion for small bowel CD, and treatment for IBD was initiated based on overall clinical picture.
Cases of perforated Meckel's with subsequent abscess formation have been found in adults [7], but there are few in children [3,4]. Tese rare cases of perforation made us suspect a Meckel's diverticulum in our patient [4]. Our particular case is unique because it is one of few case reports of a child with chronic gastrointestinal symptoms (ultimately, he had 9 months of abdominal pain with nonbloody diarrhea), laboratory fndings, histology, and imaging showing bowel perforation, raising suspicion for a diagnosis of IBD, but later found to have Meckel's instead. Our patient's iron defciency, anemia, and hypoalbuminemia at initial presentation were likely a result of chronic, unrecognized slow gastrointestinal bleeding. Although there are some case reports of Meckel's diverticula found in patients with Crohn's disease [8], a subsequent study of 877 patients with CD found no increased incidence of Meckel's in patients with CD [9].
Clinicians should consider Meckel's diverticulum as a potential cause of surgical abdomen such as abdominal abscess or intestinal perforation. Additionally, when a patient presents with clinical features of IBD but histology does not support diagnosis, or patient is not responding to reasonable therapy, other diagnoses which may have overlapping presentation should be considered. Clinicians should certainly have a broad diferential on initial assessment when patients (children any age) present with Case Reports in Pediatrics symptoms of abdominal pain, blood in stools, diarrhea, fever, anemia, elevated infammatory markers, and/or fndings of infammatory bowel disease in imaging such as CT abdomen/pelvis. Once patient undergoes esophagogastroduodenoscopy/colonoscopy with biopsies that are not convincing for infammatory bowel disease as well as poor response to conventional therapies for infammatory bowel disease. Patient should be followed very closely mostly if symptoms of bloody stools consider performing a Meckel's scan to look for Meckel's diverticulum.

Data Availability
Te data supporting the current study are available from the corresponding author upon request.

Consent
Written informed consent was obtained from the patient's legal guardian for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.