The majority of<unk> s are benign, while some are malignant. The World Health Organization (WHO) classification scheme places<unk><unk> s into three main categories, which emphasize the<unk>  grade rather than the anatomical origin. In practice, those<unk> s termed well or intermediately differentiated<unk> s in the WHO scheme are sometimes called "islet cell<unk> s". The high-grade subtype termed<unk>  cancer (NEC) in the WHO scheme, is synonymous with "islet cell carcinoma". +Types of<unk>  based on hormones produced Type Relative incidence Typical location of<unk>  Biomarkers Symptoms Insulinoma 35–40% Head, body, tail of pancreas insulin, proinsulin, C-peptide Hypoglycemia Gastrinoma 16–30% Gastrinoma triangle gastrin, PP *Abdominal pain *Refractory peptic ulcer disease *Secretory diarrhea VIPoma <10% Distal pancreas (body and tail) VIP *Profuse watery diarrhea *Dehydration *Hypokalemia *Achlorhydria Somatostatinoma <5% Pancreatoduodenal groove, ampullary, periampullary somatostatin *Diabetes mellitus *Cholelithiasis *Steatorrhea *Anemia *Weight loss PPoma Head or pancreas<unk>  polypeptide Glucagonoma 1% Body and tail of pancreas glucagon, glycentin *Necrolytic migratory erythema *Diabetes mellitus *Diarrhea *Deep vein thrombosis Relative incidence is given as percentage of all functional<unk> s.
Pancreatic neuroendocrine tumor
Small intestine neuroendocrine tumor
Metastatic insulinoma
Acinar cell carcinoma of the pancreas
Glucagonoma
Pancreatic mucinous cystic neoplasm
Insulinoma
Goblet cell carcinoid