Pancreatic Manifestations of Systemic Diseases

Metabolic Disorders - Sweet & Iron Woes

• Diabetes Mellitus (DM):
  • Type 1: Autoimmune insulitis, β-cell destruction, islet atrophy/fibrosis. Absolute insulin deficiency.
  • Type 2: Insulin resistance. Islet amyloid (IAPP/amylin) deposition, β-cell dysfunction/loss.
  • Both: Can lead to Pancreatic Exocrine Insufficiency (PEI). Risk of pancreatitis, pancreatic cancer ↑.
• Hemochromatosis: Iron overload.
  • Pancreas: Hemosiderin deposition in acinar & islet cells (esp. β-cells).
  • Effects: Fibrosis, chronic pancreatitis, exocrine & endocrine dysfunction (Diabetes Mellitus - "Bronze Diabetes").
  • Stain: Perls' Prussian blue for iron. ⭐ > "Bronze diabetes" in hemochromatosis results from iron deposition damaging pancreatic β-cells, leading to insulin deficiency.

Infections - Pancreatic Bug Invasion

• Pathogens can cause pancreatitis or pancreatic abscess.
• Viral culprits:
  • Mumps (classic; parotitis-pancreatitis)
  • Coxsackie B (commonest viral)
  • CMV, HIV, Hepatitis (A,B,C,E), EBV, VZV
• Bacterial invaders:
  • Mycoplasma, Legionella, Salmonella, Campylobacter
  • TB (granulomatous pancreatitis)
  • Ascending infection (E.coli, Klebsiella) from biliary tract
• Fungal infections:
  • Candida spp. (severe necrotizing pancreatitis, immunocompromised)
• Parasitic causes:
  • Ascaris lumbricoides (ductal obstruction)
  • Toxoplasma, Cryptosporidium (immunocompromised)

⭐ Mumps virus is a classic cause of acute pancreatitis, particularly in unvaccinated individuals, often following parotitis.

Autoimmune Conditions - Self-Inflicted Sting

• Autoimmune Pancreatitis (AIP): Immune-mediated inflammation. Two main types:
  • Type 1 AIP (LPSP - Lymphoplasmacytic Sclerosing Pancreatitis):
    • Part of IgG4-Related Disease (IgG4-RD).
    • ↑ Serum IgG4.
    • Histology: Storiform fibrosis, obliterative phlebitis, IgG4+ plasma cells.
    • Multi-organ involvement common (e.g., cholangitis, sialadenitis).
  • Type 2 AIP (IDCP - Idiopathic Duct-Centric Pancreatitis):
    • Normal serum IgG4.
    • Associated with Inflammatory Bowel Disease (IBD), particularly Ulcerative Colitis.
    • Histology: Granulocytic Epithelial Lesions (GELs) in ducts.
    • Usually pancreas-specific.
• Both AIP types generally respond well to corticosteroid therapy.
• Other conditions: Sjögren's syndrome, Systemic Lupus Erythematosus (SLE) can also manifest with pancreatitis.

⭐ Type 1 AIP often presents with a "sausage-shaped" pancreas on imaging and is a key manifestation of IgG4-Related Disease.

Vascular & Genetic Links - Flow & Flaw Factors

• Vascular Compromise:
  • Ischemia: Atherosclerosis, vasculitis (e.g., Polyarteritis Nodosa), shock, thromboembolism.
  • Hypoperfusion states → acute pancreatitis.
• Genetic Predispositions:
  • Cystic Fibrosis (CFTR): Inspissated secretions, chronic pancreatitis, exocrine insufficiency.
  • Hereditary Pancreatitis (PRSS1, SPINK1, CTRC): Recurrent acute pancreatitis.
  • Von Hippel-Lindau (VHL): Pancreatic cysts, serous cystadenomas, NETs.
  • Shwachman-Diamond Syndrome (SDS): Exocrine pancreatic insufficiency.

⭐ Patients with hereditary pancreatitis (e.g., PRSS1 mutations) have a significantly increased lifetime risk (up to 40-50%) of developing pancreatic cancer.

High‑Yield Points - ⚡ Biggest Takeaways

• Cystic fibrosis: Leads to exocrine pancreatic insufficiency, malabsorption, and CF-related diabetes (CFRD).
• Hemochromatosis: Iron deposition causes pancreatic fibrosis and diabetes mellitus ("bronze diabetes").
• Autoimmune pancreatitis (AIP): Often IgG4-related, presents as sausage-shaped pancreas, responds to steroids.
• Metabolic causes: Hypertriglyceridemia (> 1000 mg/dL) and hypercalcemia can induce acute pancreatitis.
• Mumps virus: A known infectious cause of acute pancreatitis, especially in unvaccinated individuals.
• Von Hippel-Lindau disease: Associated with pancreatic cysts and neuroendocrine tumors.