A 63-year-old woman with a 4 1/2-year history of diabetes mellitus presented with an ulcerating rash, primarily on the shins, groin, and face (Panel A); cheilitis (Panel B); and glossitis. Her symptoms had been worsening for 4 years despite specialized wound care. In addition, she noted concurrent weight loss, depression, abdominal pain, and intractable nausea. She was taking 500 mg of metformin daily.
Given her history of diabetes mellitus and the skin findings, abdominal computed tomography was performed, and glucagon levels were measured. An enhancing, lobulated mass measuring 7 cm in diameter was found in the tail of the pancreas, and the patient's fasting glucagon level was elevated, at 890 pg per milliliter (normal range, 0 to 80). The mass was resected, and pathological examination of the specimen confirmed a diagnosis of glucagonoma. Glucagonomas are rare neuroendocrine tumors…