Neuroendocrine Tumors - Eidelman

Question 1

What chemicals are notably contained in GI NET and what do they notably produce (former name)?

Answer 1

Contain Chromogranin A-neuroendocrine cell markers

Used to be called “Apudomas” because they Decarboxylated Amine precursor uptake cells.

They produce monoamine neurotransmitters such as serotonin, dopamine and histamine..

Question 2

Neoplasms calassified as NETs

Answer 2

Multiple endocrine neoplasia, type 1 and type 2/medullary thyroid carcinoma
Carcinoid tumors
Pheochromocytoma/paraganglioma
Poorly differentiated/small cell/atypical lung carcinoid
Small cell carcinoma of the lung
NETs occur most often in the GI system

Question 3

Biological behavior of NETs

Answer 3

Slow growing
 Secretion of biologically active peptides/amines (sometimes precursors so no symptoms, if hormone production is not symptomatic then symptoms correspond to invasion, obstruction or metastases of tumor growth)
 Somatostatin receptors (Present in almost all GI, cells become cancers often)

Question 4

What is the carcinoid tumor that most often metastasizes? Why is it often not found?

Answer 4

Small intestinal carcinoids. Multiple tumors that are under the normal looking mucosa. Secretes fibrosis into serosa around it. Looks normal in endoscopy. May present with occult bleeding if erosion of blood vessel and mucosa. Usually presents with diarrhea or obstruction (from fibrosis) and is often mistaken for IBS.

Question 5

3 types of gastric carcinoid tumors

Answer 5

Type 1: Associated with pernicious anemia and chronic atrophic gastritis. Hypergastrinemia.

Type 2: Associated with Zollinger-Ellison Syndrome (also hypergastrinemia)

Type 3: Sporadic gastric carcinoids without increased gastrin levels. More aggressive, needs aggressive treatment.

Question 6

Signs and symptoms of carcinoid syndrome

Answer 6

Abdominal pain
Rectal bleeding
Melena
Intestinal obstruction
Constipation
Abdominal mass
Diarrhea
GI bleeding
Right sided heart valvular lesions (from serotonin in the right heart)
Tryptophan deficiency (causes pellagra, CHF and other symptoms)

Secretion of serotonin into systemic circulation (from metastasis to liver)

Elevated urinary 5HIAA, elevated plasma chromogranin A

Metastatic disease especially in stomach and small bowel (even though appendix has the highest number of tumors).

Question 7

Treatment of Carcinoid

Answer 7

Antihistamines

Bronchodilators (lung carcinoid)

Octreotide (for Carcinoid Syndrome-diarrhea flushing and tumor growth)

Peptide receptor radionucleotide therapy (new and exciting)

Surgery to limit growth and remove tumor

Question 8

List of types of pancreatic endocrine tumors

Answer 8

Gastrinomas

Insulinomas
-Islet B-cell tumor. Increased insulin: confusion, headache, disorientation, coma, sweating, tremor. Hypoglycemia.

Somatostatinomas
-Islet D cell tumors. Huge pancreatic mass, no direct symptoms but increased somatostatin: diabetes, diarrhea, cholecystitis (decreased motility and contraction of gallbladder)

VIPomas
-rare cause of secretory watery diarrhea. Tumor of Islet D1 cells. Hypokalemic acidosis.

Glucagonomas

Treatment:

Remove or suppress with somatostatin.

Question 9

Zollinger-Ellison syndrome

Clinical features, prognosis, treatment

Answer 9

Gastrin producing tumor

25-50% of gastrinomas are associated with MEN I (pancreas parathyroid and pituitary tumors)
All have hypercalcemia-test for this in family members

Clinical features: abdominal pain, ulceration (95%) that are H. pylori negative (because increased acid), multiple ulcers distal to duodenal bulb, inflammatory diarrhea, steattorrhea (because enzymes aren’t working)-not enough bicarbonate.

Prognosis:
50-70% are malignant

Treatment:
Surgery (laprotomy to look for tumor, remove it and they will heal)
PPIs
Octreotide (long acting somatostatin to lower gastrin levels by decreasing G cell secretion)