n. a usually malignant pancreatic tumour of the alpha cells of the *islets of Langerhans that secretes excessive amounts of glucagon and causes impaired glucose tolerance or diabetes, a specific dermatitis, and weight loss.
any tumour arising in a cell of the pancreatic *islets of Langerhans. These tumours, which include *insulinomas, *glucagonomas, and *somatostatinomas, form one of the two major subclasses of gastrointestinal neuroendocrine tumours, the other being the *carcinoid tumours.... islet cell tumour
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