Congenital anomalies of the pancreas

Congenital anomalies of the pancreas are structural abnormalities that result from improper development of the pancreas during embryogenesis. The most common anomaly is pancreas divisum. Others include annular pancreas, dorsal pancreatic agenesis, and ectopic pancreas. Although most individuals are asymptomatic, some may present with abdominal pain, recurrent pancreatitis, or features of gastrointestinal obstruction, depending on the specific anomaly. Diagnosis is typically made with cross-sectional imaging. Asymptomatic individuals generally do not require treatment. Symptomatic patients may be managed with conservative measures, endoscopic therapy, or surgical intervention.

Definition ^[1]

Pancreas divisum is a congenital anomaly of the pancreas, characterized by separate drainage of the dorsal and ventral pancreatic ducts.

Epidemiology ^[1][2]

• Prevalence: 4–15% ^[2]
• Demographics: higher prevalence in US and European populations than in Asian and African populations

Etiology ^[1][2]

• Arises from failure of fusion of the dorsal and ventral pancreatic buds by the 8th week of embryonic development (See "Embryology of the pancreas.")
• Associated anomalies include:
  • Annular pancreas
  • Anomalous pancreaticobiliary junction and choledochal cysts
  • Partial dorsal pancreatic agenesis

Classification ^[1][2]

Pancreas divisum is classified into three variants.

• Complete (classic)
  • Most common variant, accounting for ∼ 70% of cases ^[1]
  • Anatomy
    • Ventral pancreatic duct opens into the major papilla
    • Dorsal pancreatic duct opens into the minor papilla
    • No communication between the two ducts
• Incomplete
  • Accounts for ∼ 15% of cases ^[1]
  • Anatomy: similar to complete variant, except that a small communicating branch exists between the ventral and dorsal pancreatic ducts
• Reverse
  • Uncommon
  • Anatomy
    • Dorsal (main) pancreatic duct drains into the major papilla instead of the minor.
    • Ventral pancreatic duct drains into the minor papilla instead of the major.

Clinical features^[1][2]

• Most individuals are asymptomatic, with the anomaly detected incidentally.
• Symptoms include:
  • Abdominal pain
  • Recurrent acute pancreatitis
  • Chronic pancreatitis

Diagnosis ^[1][2]

• Secretin-enhanced MRCP
  • Imaging modality of choice
  • Higher diagnostic sensitivity than standard MRCP (86% vs. 52%) ^[2]
• Endoscopic ultrasound
  • High diagnostic accuracy, with a sensitivity of 87–95% ^[1]
  • Characteristic findings include:
    • Absence of the stack sign
    • Presence of crossed duct sign
• ERCP
  • Gold standard test to confirm diagnosis
  • Generally reserved for cases requiring therapeutic intervention because of its invasiveness and risk of complications

Differential diagnoses ^[1][2]

The differential diagnosis includes pseudopancreas divisum caused by obstruction of the main pancreatic duct (e.g., from a tumor, stricture, or focal pancreatitis).

Management ^[1][2][3]

General principles

• Further evaluation or therapeutic management is not necessary for asymptomatic individuals with incidentally found pancreas divisum.
• The role of endoscopic therapy for symptomatic individuals is controversial.

Conservative management

• Indicated for mild or infrequent symptoms (e.g., pancreatic-type abdominal pain)
• Treatment may include:
  • A low-fat diet
  • Non-opioid analgesics
  • Pancreatic enzyme supplementation

Endoscopic therapy

Considered the first-line intervention for symptomatic patients requiring therapy

• Indications
  • Recurrent acute pancreatitis
  • A single episode of severe pancreatitis with no other identifiable cause
  • Chronic pancreatitis with a modifiable target (e.g., dilated dorsal duct)
  • Not indicated for the treatment of abdominal pain alone
• Procedures
  • Minor papilla endoscopic sphincterotomy
  • Minor papilla orifice balloon dilation
  • Transminor papilla dorsal duct stenting
• Outcomes: Response is variable and determined by clinical presentation.

Surgical therapy

• Indications
  • Failed endoscopic intervention or
  • Altered anatomy preventing endoscopic therapy
• Procedures
  • Minor papilla sphincterotomy
  • Sphincteroplasty
• Outcomes:
  • Efficacy comparable to endoscopic therapy
  • Higher procedural risk compared with endotherapy

Complications ^[1]

• Recurrent acute pancreatitis
• Chronic pancreatitis

Definition ^[2][4]

Annular pancreas is a rare congenital anomaly characterized by a complete or partial ring of pancreatic tissue encircling the second portion of the duodenum.

Epidemiology

• Prevalence: ∼ 0.0045% in the general population ^[4]
• Age: manifests most often in infancy, but some individuals remain asymptomatic until adulthood^[2]

Etiology ^[2][4]

• Arises from defective migration and malrotation of the ventral pancreatic bud during embryonic development
• Common associated conditions include:
  • Down syndrome
  • Congenital heart defects
  • Intestinal malrotation
  • Duodenal atresia
  • Meckel diverticulum

Classification ^[2][5]

• Based on duodenal encirclement
  • Complete: annulus fully encircles the duodenum
  • Incomplete: annulus does not entirely encircle the duodenum
• Based on tissue location
  • Extramural: a band of pancreatic tissue overlies the duodenum, with a duct encircling it and connecting to the main pancreatic duct
  • Intramural: pancreatic tissue is located within the duodenal wall, with small ducts draining directly into the intestinal lumen
• Portal annular pancreas: rare variant where pancreatic tissue fuses around the portal vein and superior mesenteric veins

Clinical features ^[2][4][5]

Many patients are asymptomatic; when present, clinical features vary with age.

• Prenatal: polyhydramnios
• Neonates
  • Feeding difficulties
  • Abdominal distention
  • Nonbilious or bilious vomiting
• Adults
  • Abdominal pain
  • Nausea and/or vomiting
  • Postprandial fullness
  • Symptoms of pancreatitis
  • Peptic ulcer disease
  • Jaundice (infrequent)

Diagnostics ^[2][4][5]

• Prenatal ultrasound or abdominal radiograph may show features of duodenal obstruction (e.g., double bubble sign).
• Cross-sectional imaging
  • Circumferential or crescent-shaped pancreatic tissue encases the second portion of the duodenum.
  • Duodenal wall thickening, narrowing, and proximal dilatation may be visualized.

Differential diagnoses ^[2][4]

• Causes of duodenal wall thickening, e.g.:
  • Duodenal adenocarcinoma
  • Duodenal leiomyoma
• Causes of duodenal obstruction, e.g.:
  • Duodenal atresia
  • Duodenal web
  • Intestinal malrotation

Management ^[2][4][5]

• Asymptomatic: Treatment is generally not required.
• Symptomatic
  • Surgical intervention may be considered.
  • Bypass procedures (e.g., duodenoduodenostomy) are preferred over resection of the annular tissue.

Complications ^[2][4]

• Duodenal obstruction
• Acute pancreatitis
• Chronic pancreatitis
• Biliary obstruction
• Peptic ulcer disease

Definition ^[2][5]

Dorsal pancreatic agenesis is a rare congenital anomaly in which the dorsal pancreatic bud fails (either partially or completely) to develop.

Epidemiology ^[5]

Approx. 100 cases have been described in the literature.

Etiology ^[2]

• Arises from failed development of dorsal pancreatic bud during embryonic development
• May be associated with heterotaxy syndrome

Clinical features ^[2][5]

• Often asymptomatic and detected incidentally on cross-sectional imaging
• Symptoms include:
  • Nonspecific abdominal pain
  • Symptoms of pancreatitis
  • Symptoms of diabetes mellitus

Diagnosis ^[2]

Cross-sectional imaging shows a truncated pancreas and the absence of the dorsal pancreatic duct.

Differential diagnoses ^[2]

Pancreatic atrophy may be caused by conditions such as:

• Pancreatic lipomatosis
• Pancreatic cancer
• Chronic pancreatitis

Management ^[2]

There is no disease-specific therapy for dorsal pancreatic agenesis.

Complications ^[2]

• Recurrent pancreatitis
• Diabetes mellitus

Definition ^[5]

Ectopic pancreas is a congenital anomaly in which pancreatic tissue is located outside the normal pancreas, with no anatomical or vascular connection to the native organ.

Epidemiology

• Prevalence: 0.3–13.7% ^[2]
• Sex: ♂ = ♀ ^[5]

Etiology ^[2][5]

• Arises from the misplacement of pancreatic tissue during embryonic foregut rotation
• Most common locations:
  • Gastric antrum along the greater curvature
  • Proximal duodenum
  • Proximal jejunum
• Other reported sites include:
  • Intra-abdominal: liver, gallbladder, spleen
  • Extraperitoneal: retroperitoneum, mediastinum, female reproductive tract

Classification ^[5]

Ectopic pancreatic tissue is classified histopathologically according to the Heinrich classification.

• Type 1: contains acini, ducts, and endocrine islet cells
• Type 2: contains acini and ducts, but no islet cells
• Type 3: contains only pancreatic ducts

Clinical features ^[2][5]

• Most individuals are asymptomatic, with lesions discovered incidentally.
• Symptoms may be due to mass effect and include:
  • Dyspepsia
  • Epigastric pain
  • Postprandial nausea and/or vomiting
  • Bowel obstruction
  • Intussusception
  • Hemorrhage
  • Weight loss
  • Malabsorption
  • Acute pancreatitis
  • Chronic pancreatitis

Diagnosis

Imaging ^[2]

• Typically appears as a nonspecific, endophytic, solid, submucosal mass
• Enhancement pattern is similar to that of the normal pancreas.
• A small central umbilication, representing a remnant of a primitive pancreatic duct, may be visible.

Differential diagnoses ^[2]

Submucosal lesions of the gastrointestinal tract, including:

• Gastrointestinal stromal tumor (GIST)
• Neuroendocrine tumor
• Duplication cyst

Management ^[2]

Symptomatic individuals may require surgical intervention.

Complications ^[2][5]

Ectopic pancreatic tissue is susceptible to the same pathologies as the native pancreas.

• Pancreatitis (acute or chronic)
• Groove pancreatitis: associated with ectopic tissue located between the duodenal wall and the pancreatic head
• Cystic degeneration and pseudocyst formation
• Neoplastic transformation (rare)
  • Pancreatic intraepithelial neoplasia
  • Ductal adenocarcinoma
  • Neuroendocrine tumors (e.g., insulinoma)
• Islet cell adenomatous hyperplasia with subsequent hyperinsulinism