What is an aberrant pancreas?

Aberrant Pancreas: Definition, Diagnosis, and Management

An aberrant pancreas, also known as pancreatic rest, heterotopic pancreas, or ectopic pancreas, is defined as pancreatic tissue located outside the normal pancreas with no anatomical, neural, or vascular connection to the main pancreatic gland. This congenital anomaly was first described in 1727 and is most commonly found in the stomach, duodenum, and proximal small bowel 1, 2.

Characteristics and Epidemiology

• Aberrant pancreas is typically found in the upper gastrointestinal tract, with the most common locations being:

  • Gastric antrum (especially along the greater curvature)
  • Duodenum
  • Proximal jejunum
  • Less commonly in the ileum 3, 1, 2

• On endoscopy, it often appears as a subepithelial nodule with a central umbilication on its surface, though this finding is not universally present 3

• Histologically, aberrant pancreas contains normal pancreatic tissue that may include:

  • Acinar cells
  • Ductal structures
  • Islet cells
  • May have all components or only some elements of pancreatic tissue

Clinical Presentation

Most cases of aberrant pancreas are asymptomatic and discovered incidentally during endoscopy, surgery, or imaging studies. When symptomatic, presentations may include:

• Abdominal pain (most common symptom)
• Nausea and vomiting
• Gastrointestinal bleeding
• Obstruction (particularly when located near the pylorus)
• Symptoms of pancreatitis if the tissue becomes inflamed 1, 2
• Rare complications include intussusception (especially in children) 4

Diagnosis

Diagnosis of aberrant pancreas can be challenging and often requires multiple modalities:

1. Endoscopy: May reveal a subepithelial mass, often with central umbilication
2. Endoscopic Ultrasound (EUS): Shows a hypoechoic, heterogeneous lesion typically in the submucosal layer (third layer) 3, 5
3. Cap-assisted Endoscopic Submucosal Resection (ESMR): May be used to obtain adequate histologic samples 3
4. Cross-sectional imaging (CT/MRI): May identify the lesion but cannot definitively diagnose aberrant pancreas
5. Definitive diagnosis: Requires histopathological examination of tissue samples

Differential Diagnosis

The differential diagnosis for aberrant pancreas includes other subepithelial lesions:

• Gastrointestinal stromal tumors (GISTs)
• Leiomyomas
• Lipomas
• Carcinoid tumors
• Varices
• Duplication cysts
• Inflammatory fibroid polyps 3

Management

Management depends on symptoms and diagnostic certainty:

1. Asymptomatic lesions:

   • If diagnosis is confirmed by adequate sampling, observation is appropriate
   • Regular follow-up may be considered

2. Symptomatic lesions:

   • Endoscopic resection for smaller, accessible lesions
   • Surgical resection for larger lesions or those causing significant symptoms 5

3. Uncertain diagnosis:

   • Tissue sampling is recommended to exclude other pathologies, particularly malignancies

Potential Complications

Though rare, aberrant pancreas can develop complications:

• Inflammation (pancreatitis in the ectopic tissue)
• Cystic degeneration
• Malignant transformation (extremely rare but documented) 6
• Obstruction of hollow viscera
• Intussusception, particularly in pediatric cases 4

Follow-up

For resected lesions, follow-up is generally not required if complete resection is achieved. For non-resected lesions, periodic endoscopic surveillance may be considered, though there are no standardized guidelines for the frequency of follow-up.

Aberrant pancreas should be considered in the differential diagnosis of subepithelial lesions of the upper gastrointestinal tract, particularly when the characteristic endoscopic appearance of a submucosal nodule with central umbilication is present.