Glucagonoma is a rare pancreatic tumor that produces excess glucagon hormone. It originates from alpha cells in the pancreas and can spread to the liver. Symptoms include diarrhea, weight loss, and a migratory rash. The rash is often the first symptom and affects the skin between the genitals and anus before spreading. Surgery to remove the tumor can cure the condition, but it often spreads to the liver and is difficult to treat with chemotherapy.