Early diagnosis and surgical management in adult intussusceptions caused by ectopic pancreas

Adult intussusception comprises of only 5% of all intussusception cases with majority occurring in children and accounts for only 1–5% cases of bowel obstruction in adults. Ectopic pancreas is an infrequent anomaly defined as pancreatic tissue that lacks anatomical or vascular communication with the normal body of the pancreas. When reported it is mostly found in the stomach and small intestines but seldom in the colon. We present a case of a 31-year-old male who presented with symptoms of an acute abdomen which was diagnosed as an intussusception of an unknown etiology on a contrast-enhanced computed tomography (CT). The patient was resuscitated and immediately operated on and underwent a right hemicolectomy and eventually an end ileostomy formation. No cause for the intussusception was apparent intra-operatively but histological examination of the resected bowel specimen demonstrated ectopic pancreas. The patient had a very short recovery time without incident which may be attributed to his age and absence of co-morbidities. He was discharged a follow-up plan to discuss the reversal. The patient went on to have reversal of his stoma after six months of the initial surgery with a very good outcome.


INTRODUCTION
Intussusception is defined as the invagination of a segment of bowel within an immediately adjacent segment and almost invariably occurs from proximal to distal. It is most frequent in children with incidence peaking at 5-10 months of age, becoming less common above two years and is predominantly rare in adults. Adult intussusception represents just 5% of all cases of intussusception and accounts for only 1-5% of cases of adult bowel obstruction [1][2][3]. Colo-colic type intussusception has been found to be more common in adults [4]. Unlike children, in whom around 90% of cases are idiopathic, adult intussusception is usually secondary to an underlying pathology, such as polyps, Meckel's diverticulum, strictures, benign neoplasms, or carcinomas [3]. The presentation is mostly insidious in adults, with nonspecific symptoms but can lead to intestinal obstruction and ischemia of the advancing bowel. The primary management in children with uncomplicated intussusception consists of nonoperative reduction with air or barium enema. Adults, however, will typically require surgical intervention to identify the underlying pathology.
Ectopic pancreas is defined as pancreatic tissue that lacks anatomical or vascular communication with the normal body of the pancreas [5]. It is an infrequent congenital anomaly with an incidence of 0.55-13.7% on autopsy series [6,7]. It has been reported to be most commonly located in the stomach (25-38% of cases), the duodenum (17-36% of cases), and the jejunum (15-22% of cases) although seldom described in other locations, such as Meckel's diverticulum, colon, gallbladder, umbilicus, fallopian tube, mediastinum, spleen, liver and, as in our case, the ileum [8][9][10].
A literature review of 528 cases identified the prevalence of ileal heterotopic pancreas to be just 0.2% [11]. Ectopic pancreas (EP) usually presents in the form of small yellow nodules varying in size from 1 to 5 mm, thus can be misdiagnosed as a lipoma as reported on the primary CT scan in our patient's case. In descending order of occurrence, the involved histologic layers are the submucosa, muscularis propria, and serosa [12]. They are classified according to the Heinrich classification system. Clinically significant lesions tend to be larger than 1.5 cm and involve or are adjacent to the mucosa [13].
Ectopic pancreas in the small intestine is typically benign and therefore most cases are asymptomatic, being discovered incidentally during endoscopy or surgery for another presentation or at autopsy. When symptomatic, patients can present with bleeding, pancreatitis and rarely symptoms associated with malignant transformation or, as in our case, bowel obstruction due to intussusception [8,[14][15][16][17]. In some cases it has led to death, as reported in literature [18].
We describe a rare case of an adult presenting with intussusception secondary to EP.

CASE REPORT
A 31-year-old male with no significant past medical history or previous abdominal operations presented with a 1-day history of severe lower abdominal pain, multiple episodes of vomiting, and loose stools. On examination, he had generalized abdominal tenderness with peritonism and absent of bowel sounds. Blood tests on admission displayed a raised white cell count (WCC) of 16 × 10 9 /L, C-reactive protein (CRP) of <0.6 mg/L, and lactate of 6. A contrast-enhanced CT abdomen and pelvis was performed on a suspicion of acute abdomen caused by bowel ischemia. However, it revealed ileo-colic intussusception (Figures 1 and 2). A 26 mm fat density opacity representing a possible lipoma as a lead point.
The patient was resuscitated with intravenous fluids, antibiotics, and analgesia, and was taken to theatre for an emergency laparotomy within 3 hours of presentation. Intra-operatively, 50 cm of terminal ileum was found intussuscepted into 10 cm of ascending colon ( Figure  3). Manual reduction was attempted without success. So, a right hemicolectomy was performed. Initially a defunctioning double barrel stoma formation was planned but not performed at this time due to significant edema of the bowel. After discussion, consensus was for a re-look laparotomy once the patient had stabilized with a view for stoma formation as the ideal approach. Approximately 24 cm of ileum and 17 cm of colon including cecum, ascending and proximal transverse colon were resected and a temporary primary anastomosis was formed. The abdomen was closed by a vacuum-assisted closure dressing. No visible or palpable mass was identified intraoperatively but histological examination of specimen concluded a focal ectopic pancreas. However, grading of the ectopic pancreatic tissue had not been done histologically because of the patchy nature of the tissue.
The patient was initially treated in the surgical intensive recovery unit post-operatively then stepped down to the ward. He required rectus sheath infusion and morphine patient controlled analgesia. The patient was treated with intravenous antibiotics and parenteral nutrition.    J Case Rep Images Surg 2020;6:100078Z12SK2020. www.ijcrisurgery.com  On day 8, the patient returned to the theatre for relook laparotomy, washout, closure of abdominal wall, and formation of end ileostomy. He recovered well in intensive treatment unit (ITU) post-operatively. He was extubated on day 9 and stepped down to the ward on day 11.
The patient's symptoms slowly resolved and he recovered well. He was discharged on day 25 with followup arranged for review and discussion of stoma reversal. His stoma was reversed electively after six months with a very good outcome. He was discharged with a long-term follow-up plan.

DISCUSSION
Even if symptomatic, the pre-operative diagnosis of EP still remains challenging with imaging studies such as ultrasonography, CT, and endoscopy, not being specific as demonstrated in our case. Definitive diagnosis is reached with histopathology.
When EP has previously been located in the ileum causing intussusception, often a coexisting Meckel's diverticulum has been noted, which is thought to exacerbate the ability of the EP to act as a lead point for intussusception [19,20]. Isolated EP of the ileum causing intussusception without the presence of Meckel's diverticulum, as reported here, is particularly rare. Cases of ileal pancreatic heterotopia causing intussusception has been described in children up to the age of 12 [21]. We provide a summary of all reported cases of adult intussusception caused by ectopic pancreas in literature (Table 1).
Manual reduction in our case was unsuccessful. Previous reviews recommend that the treatment of adult intussusception is resection of the intussusception mass without prior attempts to reduce it. The vast majority of adults with intussusception have an underlying pathology as the cause [22][23][24].

CONCLUSION
The role of laparoscopy in the management of intussusception has been described as an attractive option, especially in the emergency setting in hemodynamically stable patients with non-conclusive imaging. Although this may go on to require laparotomy in most adults and in children whose manual reduction fails, with confirmation of the diagnostic suspect of intussusception. It may entail smaller subsequent laparotomy incisions, shorter bowel manipulation time along with general reduction in post-operative hospital stay, and possible reduction in analgesia requirements, surgical site infections, cardiac respiratory complications, and post-operative mortality. However, in this case laparoscopy was not an option. Most of the times an adult has an underlying pathology for intussusception that will require proper exploration and resection. In some cases endoscopic approach has also been described as a safe and effective approach especially when found in upper gastrointestinal tract especially in the stomach. *********

Author Contributions
Smriti Karki -Conception of the work, Design of the work, Acquisition of data, Analysis of data, Interpretation of data, Revising the work critically for important intellectual content, Final approval of the version to be published, Agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved Hina Aziz -Acquisition of data, Analysis of data, Interpretation of data, Drafting the work, Final approval of the version to be published, Agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved Joseph Watfah -Conception of the work, Design of the work, Revising the work critically for important intellectual content, Final approval of the version to be published, Agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved