Glucagonoma
Glucagonoma is a rare, usually malignant alpha-cell tumor of the pancreas that classically causes new-onset diabetes, weight loss, and necrolytic migratory erythema through unopposed glucagon excess. Diagnosis rests on a markedly elevated fasting glucagon level and pancreatic imaging. Octreotide controls symptoms rapidly, and surgical resection of the primary tumor is the definitive, potentially curative treatment.
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What this article covers
- Overview
Definition: glucagonoma is a rare functioning pancreatic neuroendocrine tumor arising from the alpha islet cells of the pancreas that autonomously secretes glucagon.
- Epidemiology
Rarity: glucagonoma is an exceedingly rare pancreatic neuroendocrine tumor; published estimates place the incidence near 1 case per 20 million person-years.
- Risk factors
Germline MEN1 mutation: a family history of MEN1 (parathyroid, pituitary, and pancreatic tumors) or a known MEN1 mutation raises the risk of a pancreatic alpha-cell tumor, although glucagonoma is one…
- Pathophysiology
Cell of origin: glucagonoma arises from the alpha islet cells of the pancreas, the same cells that normally release glucagon in response to hypoglycemia.
- Clinical features
Diabetes: new-onset or worsening hyperglycemia that is usually mild and frequently does not require pharmacologic treatment.
- Differential diagnosis
Type 2 diabetes mellitus: a far more common cause of new-onset hyperglycemia, but it lacks the migratory erosive rash, marked weight loss, and elevated glucagon level of glucagonoma.
- Diagnosis
What establishes the diagnosis: a markedly elevated fasting plasma glucagon level together with a pancreatic mass on cross-sectional imaging establishes the diagnosis; classically, blood glucose…
- Management
First, control symptoms: start octreotide 100 to 500 mcg subcutaneously two to three times daily, titrated to control of the rash and diarrhea, then transition to octreotide long-acting release 20 to…
- Complications
Hepatic metastasis: the liver is the most common site of spread and is frequently present at diagnosis.
- Prognosis
Rash response: NME and the catabolic symptoms typically improve within days to weeks of starting octreotide or after tumor resection.
- Prevention
No primary prevention for sporadic disease: there is no known modifiable risk factor that prevents sporadic glucagonoma.
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