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Glucagonoma

Definition: rare neuroendocrine tumor of the pancreatic α-cells that secretes glucagon
Clinical features
- Weight loss
- 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)

Mnemonic

6 D’s: dermatitis (necrolytic migratory erythema), diabetes (hyperglycemia), DVT, declining weight, depression, diarrhea.

Somatostatinoma

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)