Heterotopic Pancreas and Gastric Mucosa in Meckel’s Diverticulum: A Rare Cause of Bowel Obstruction. Our Experience and a Brief Literature Review: A Case Report

INTRODUCTION

Ectopic pancreas, also known as heterotopic, is an anatomical abhorrent condition in which pancreas tissue has raised beyond its usual place without a real anatomical, neural or vascular relationship with the main body of pancreas. It is an uncommon disease that may involve every portion of the gastrointestinal tract.

Meckel’s diverticulum is a bulge of small intestine wall present since birth and its origins from a wrong development of omphalomesenteric duct. It is present about 2% of the general population and it is frequently characterized by a habitual occurrence of ectopic tissue and approximately 4% of patients become symptomatic and require surgical excision.^1–3 Gastric mucosa, whose common complication are bleeding and ulceration, is the most common ectopic tissue present.^4,5

Heterotopic pancreas, ectopic gastric mucosa and Meckel’s diverticulum are very uncommon anatomical disorders and the presence of all three in a triad is extremely rare and often asymptomatic.⁶ Acute abdominal pain, due to perforation or bowel obstruction, and other nonspecific symptoms are reported by patients but they are not pathognomonic for this disease. Based on the pathological examination, it is possible to make a definitive diagnosis.

CASE DESCRIPTION

A 49-year-old man patient was admitted to our department in urgency with sudden abdominal pain localized in the right flank, nausea, vomiting, and diarrhea.

The patient had a history of hypertension, diabetes, and mental disability.

Physical examination on admission revealed abdominal tenderness mainly in the right flank with mild peritoneal signs of rebound and guarding. Abdominal distension and bloating were remarkable.

The laboratory exams were normal except for a neutrophilic leukocytosis; ultrasonography (US) showed diffused bowel distention without other anomalies of abdominal organs.

Computed tomography (CT) (Fig. 1) was performed and revealed huge gastric enlargement and widespread small bowel dilatation with air–fluid levels. Furthermore, the last tract of ileum appeared stretch with reduced caliber and peritoneal fluid was present. All radiological features emphasized a bowel obstruction.

The patient underwent explorative laparotomy that showed a diverticulum of the ileum about 60 cm from ileocecal valve with a bezoar inside it (Fig. 2). A segmental resection was performed.

Recovery was uneventful; oral feeding restarted on second postoperative day and normal bowel functions were restored on third postoperative day. Drains were removed on fourth postoperative day and the patient was discharged on seventh postoperative day.

DISCUSSION

Meckel’s diverticulum is the most prevalent disease of alimentary tract present in 1–3% of autopsy caused by a wrong development of omphalomesenteric duct with an incomplete closure of it.⁹ It originates from an unusual communication between the embryonic yolk sac and primitive mid-gut during first 2–3 weeks of pregnancy. In 1598, Fabricus Hildanus described for the first time a Meckel’s diverticulum but only in 1809, when Johann Friedrich Meckel explained its embryological origin, it was named in this way.

Since it involves all layers of bowel wall, including muscularis propria and adventitia, it is classified as a true diverticulum. It occurs more frequently in males compared to female.

Meckel’s diverticulum is frequently asymptomatic and it is diagnosed when complications occur or incidentally during surgery and radiological exams of small intestine.

Clinical manifestations include gastrointestinal blending, obstruction, diverticulitis and neoplasm.

In the most important series recorded by Park et al. from 1950 to 2002, only 16% of the 1,476 patients collected were symptomatic and the most common complications were bleeding (38%), obstruction (34%) and diverticulitis (28%).¹⁰

Ectopic gastric mucosa is recurrently present in about half of Meckel’s diverticulum with a reported incidence of 23–50% of the cases. Acid release from ectopic gastric mucosa may lead to ulcers and also to chronic or acute bleeding.¹¹

In 1727, the first case of pancreatic tissue in a diverticulum of the ileum was described by Jean Schultz.^12,13 Since many patients are asymptomatic the real incidence remains undetermined and prevalence data show the presence of heterotopic pancreas at 0.2% of laparotomy and at 14% of autopsies.¹³

The origin of heterotopic pancreas is unclear, but surely it seems to data back to fetal life during the process of rotation of foregut and the following fusion of the dorsal pancreatic buds with the ventral one. Some cells switch from it and develop into ectopic pancreas in any portion of the gastrointestinal tract.¹⁴ Another theory is built on the pancreatic metaplasia of endodermal tissue.¹⁵ Although heterotopic pancreas can be found in every part of the gut, it is usually found in the upper tract of gastrointestinal system.

Heterotopic pancreas may be classified into the following three types:

• Type I: With the presence of ducts, acini and endocrine islets similar to those visible in a normal pancreas.

• Type II: With a large number of acini, a few ducts and without islets.

• Type III: With several ducts, rare acini and without islets.

Pearson found heterotopic pancreas only in 3% of ileus and 6% of Meckel’s diverticulum in 589 cases.¹⁶ Another large series of 212 cases recorded by Dolan RV found only 1.4% cases of ectopic pancreas in the ileum wall and 5.2% cases in Meckel’s diverticulum.¹⁷

Patients are usually asymptomatic unless intestinal obstruction, intussusception, inflammation or malignant change onset.¹⁸ The symptoms (diverticulitis, ulceration and chemical irritation) may be caused by the release of hormones and enzymes from the ectopic tissue.

Trials focused on heterotopic pancreas and gastric mucosa in Meckel’s diverticulum are few.

Approximately half of cases of small intestinal heterotopic pancreas are asymptomatic and when symptoms occur, abdominal pain and gastrointestinal bleeding are most common.^19,20 On the contrary, the association of heterotopic pancreas and gastric mucosa in Meckel’s diverticulum may be quite symptomatic and may cause severe clinical manifestations and complications, in fact gastrointestinal bleeding is the onset symptom in these patients as well as small bowel obstruction.

Despite the development of modern diagnostic exams, the definitive diagnosis before surgery remains a challenge.

Computed tomography is first level exam in the study of small bowel diseases but still now is unknown the effective role in clinical practice for the diagnosis of heterotopic pancreas and Meckel’s diverticulum, especially in urgency. Moreover, Meckel’s diverticulum, mainly the ones smaller than 3 cm, may be difficult to distinguish from normal small bowel loops on CT-scan.²¹

According to the literature surgery is the gold standard management and a laparoscopic or open segmental small bowel resection is the right surgical choice.

Although the preoperative diagnosis is very difficult, the definitive diagnosis is based only on pathological examination of surgical resected.

CONCLUSION

Heterotopic pancreas and gastric mucosa in Meckel’s diverticulum is an extremely rare condition, often asymptomatic. Preoperative diagnosis may be challenging and often difficult. Surgical resection is the standard treatment and the definitive diagnosis is confirmed by histological examination.

REFERENCES

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