Pancreatic Tumors

PANCREATIC TUMORS

Pancreatic neuroendocrine tumors (islet cell tumors) are less common than exocrine tumors. Most are considered low grade malignancies. Some patients lack laboratory evidence of hormone overproduction. These tumors are not distinguishable from each other on the basis of gross appearance or histology.

•         Insulinoma (β-cell tumor) (most common type of islet cell tumor)

o   Produces insulin

o   Can cause hypoglycemia, sweating, hunger, confusion, and insulin coma

o   Surgical excision is curative

•         Gastrinoma (G-cell tumor)

o   Produces gastrin

o   Excess gastrin manifests as Zollinger-Ellison syndrome, which is charac-terized by thick gastric folds, elevated serum gastrin, gastric hyperacid-ity, and intractable peptic ulcers

o   Gastrinomas may arise outside the pancreas

o   May be associated with MEN I

•         Glucagonoma (α-cell tumor)

o   Produces glucagon

o   Excess glucagon causes hyperglycemia (diabetes), anemia, and skin rash

•         Somatostatinoma (δ-cell tumor)

•         Produces somatostatin

•         Excess somatostatin inhibits insulin secretion, leading to diabetes

•         Can also inhibit gastrin secretion (leading to hypochlorhydria) and cho-lecystokinin secretion (leading to gallstones and steatorrhea)

•         Prognosis is poor

•         VIPoma

o   Produces vasoactive intestinal peptide (VIP)

o   Excess VIP causes WDHA syndrome: watery diarrhea, hypokalemia, and achlorhydria

Pancreatic carcinoma is the fifth most common cause of cancer death in the United States, and the incidence is rising.

•         Most common ages 60-80

•         Smoking is a risk factor

•         Presents with only vague signs and symptoms until late in course

•         When more definitive signs and symptoms develop, they can include abdomi-nal pain, migratory thrombophlebitis, and obstructive jaundice

The tumor may occur in the head (60%), body (15%), and tail (5%). Microscopi-cally, the adenocarcinoma arises from the duct epithelium. Tumor desmoplasia and perineural invasion are common. Tumor markers for pancreatic carcinoma include CEA and CA19-9, but they are not useful screening assays.

Treatment is surgical excision (Whipple procedure). The prognosis is very poor, with 5-year survival only ~5%.

Pancreatic cystic neoplasms: Serous neoplasms account for 25% of pancreatic cystic neoplasms; most are benign (cystadenomas) and the tumors carry a mutation of VHL.

Mucinous neoplasms: Mucinous cystic neoplasms are common in women and can harbor dysplasia or carcinoma; distal pancreatectomy is curative in most cases. Intraductal papillary mucinous neoplasms are common in men and tend to arise in the head of the pancreas; GNAS mutations are common and carcinoma may arise in the neoplasm.