Heterotopic pancreas as a rare lead point of ileal intussusception mimicking acute appendicitis in a child: a case report and review of the literature.

Introduction and importance: Heterotopic pancreas is an uncommon developmental anomaly characterized by pancreatic tissue located outside the normal pancreas without anatomical or vascular continuity. Although it is most frequently identified in the stomach and duodenum, involvement of the ileum is rare, particularly in children. When present in the small intestine, it may act as a pathological lead point for intussusception, posing a considerable diagnostic challenge because the underlying lesion is often not identified by preoperative imaging. Presentation of case: We report the case of a 6-year-old Iranian boy who presented with clinical features highly suggestive of acute appendicitis. Initial ultrasonography and contrast-enhanced computed tomography did not demonstrate appendicitis, intussusception, or a definite pathological lead point. Despite negative imaging, persistent right lower quadrant tenderness, fever, leukocytosis, and progressive clinical findings prompted an exploratory laparotomy. Intraoperatively, a normal appendix and an ileo-ileal intussusception approximately 30 cm proximal to the ileocecal valve were identified. Manual reduction was unsuccessful, necessitating segmental ileal resection with primary anastomosis. Gross examination demonstrated a 3.6 × 4.0 × 5.5 cm submucosal mass protruding into the intestinal lumen and acting as the pathological lead point. Histopathological evaluation confirmed Heinrich type II heterotopic pancreas composed of pancreatic acini and ducts without identifiable islets of Langerhans, dysplasia, or malignancy, accompanied by transmural ischemic changes secondary to intussusception. The postoperative course was uneventful, and the patient remained asymptomatic throughout follow-up. Clinical discussion: Heterotopic pancreas is an exceptionally rare pathological lead point for pediatric ileo-ileal intussusception and may clinically mimic more common surgical conditions, such as acute appendicitis. Although ultrasonography is highly sensitive for detecting intussusception, characterization of the underlying lead point remains challenging, and histopathological examination is essential for definitive diagnosis. Early surgical exploration should be considered when persistent clinical suspicion outweighs nondiagnostic imaging findings. Conclusion: Ileal heterotopic pancreas should be considered in the differential diagnosis of older children presenting with atypical or recurrent intussusception, particularly when clinical findings are discordant with imaging studies. Prompt surgical management and histopathological evaluation are crucial for establishing the diagnosis and achieving excellent clinical outcomes.