Glucagonoma

Glucagonoma is a rare functioning neuroendocrine tumour arising from the alpha cells of the pancreas. The tumour releases glucagon autonomously, so hepatic glucose production continues even when the body does not need more glucose. Glucagon activates glycogenolysis, the breakdown of stored glycogen, and gluconeogenesis, the formation of glucose from non-carbohydrate substrates. The result is persistent or worsening hyperglycemia. At the same time, the liver takes up circulating amino acids for metabolic use. This creates a sustained catabolic state: muscle and adipose tissue are broken down, weight falls, and circulating amino acids become depleted. That depletion explains why the skin can become the first visible clue. Epidermal repair requires amino acids, zinc, and essential fatty acids; when these supplies are diverted or deficient, the skin develops necrolytic migratory erythema. The rash is therefore a marker of a systemic metabolic problem, not simply a local dermatologic disorder. The diabetes is often mild to moderate because pancreatic beta cells usually remain functional and can increase insulin secretion. Diabetic ketoacidosis is uncommon, although severe illness, dehydration, or inadequate treatment can still produce dangerous hyperglycemia.