Glucagonoma

• Definition: rare neuroendocrine tumor of the pancreatic α-cells that secretes glucagon
• Clinical features
  • Weight loss
  • Hyperglycemia: Impaired glucose tolerance or diabetes mellitus
  • Necrolytic migratory erythema
    • Gluconeogenesis and lipolysis lead to depletion of amino acids, especially those required for maintaining skin integrity and repair.
    • A cutaneous paraneoplastic syndrome
    • multiple areas of centrifugally spreading erythema, located predominantly on the face, perineum, and lower extremities
    • Painful and pruritic crusty patches with central areas of bronze-colored induration
    • resolve and reappear in a different location
    • Skin biopsy shows epidermal necrosis
  • Chronic diarrhea
  • Deep vein thrombosis
  • Depression
• Diagnostics: requires a high index of suspicion to make the diagnosis
  • ↑ glucagon > 500 pg/mL, ↑ blood glucose levels, normocytic normochromic anemia
• Treatment
  • Tumor resection
  • Octreotide (if tumor is inoperable)

Somatostatinoma

• Definition: a rare neuroendocrine tumor of δ-cell (D-cell) origin that is usually located in the pancreas or gastrointestinal tract and secretes somatostatin.
  • ↑ Somatostatin → ↓ secretion of the following hormones:
    • Secretin
    • Cholecystokinin
    • Glucagon
    • Insulin
    • Gastrin
    • Gastric inhibitory peptide
• Clinical features
  • Classic triad
    • Glucose intolerance/diabetes
    • Cholelithiasis
    • Steatorrhea
  • Achlorhydria
• Diagnostics
  • ↑ somatostatin, ↑ blood glucose levels
• Treatment
  • Tumor resection
  • Octreotide

VIPoma

• Definition: non-α, non-β islet cell pancreatic tumor that secretes VIP (vasoactive intestinal polypeptide)
• Pathophysiology
  • Excess VIP → ↑ relaxation of gastric and intestinal smooth muscles and cAMP activity (similar to cholera toxin) → secretory diarrhea and inhibition of gastric acid production
• Tumor location: The primary tumor is most frequently found in the pancreas.
• Clinical features
  • WDHA syndrome (watery diarrhea, hypokalemia, achlorhydria): tea-colored watery diarrhea (> 700 mL/day) → dehydration
• Diagnostics
  • ↑ Serum VIP concentration
  • Hypokalemia
  • Hypercalcemia
  • Hyperglycemia
  • Gastric achlorhydria or hypochlorhydria
• Treatment
  • Tumor resection
  • Octreotide (inhibits VIP secretion)