Chapter 45: Carcinoid Tumors Flashcards
What is a carcinoid tumor?
Tumor arising from neuroendocrine cells (APUDomas), a.k.a. “Kulchitsky cells”; basically, a tumor that secretes serotonin
Why is it called “carcinoid”?
Suffix “-oid” means “resembling”; thus, carcinoid resembles a carcinoma but is clinically and histologically less aggressive than most GI carcinomas
What are the common sites of occurrence?
Think “AIR”:
- Appendix (most common)
- Ileum
- Rectum
- Bronchus
Other sites:
- jejunum
- stomach
- duodenum
- colon
- ovary
- testicle
- pancreas
- thymus
What are the signs/symptoms?
Depends on location;
- most cases are asymptomatic
- also SBO
- abdominal pain
- bleeding
- weight loss
- diaphoresis
- pellagra skin changes
- intussusception
- carcinoid syndrome
- wheezing
Why SBO with carcinoid?
Classically = severe mesenteric fibrosis
What are the pellagra-like symptoms?
- Dermatitis
- Diarrhea
- Dementia
What causes pellagra in carcinoid patients
Decreased niacin production
What is carcinoid syndrome?
Syndrome of symptoms caused by release of substances from a carcinoid tumor
What are the symptoms of carcinoid syndrome?
Remember the acronym “B FDR”:
- Bronchospasm
- Flushing (skin)
- Diarrhea
- Right-sided heart failure (from valve failure)
Why does right-sided heart failure develop but not left-sided heartfailure?
Lungs act as a filter (just like the liver); thus, the left heart doesn’t see all the vasoactive compounds
Classic cardiac complication with carcinoid syndrome?
Tips:
- Tricuspid Insufficiency
- Pulmonary Stenosis
What is the incidence of carcinoid SYNDROME in patients who havea carcinoid TUMOR?
≈10%
What released substances cause carcinoid syndrome?
Serotonin and vasoactive peptides
What is the medical treatment for carcinoid syndrome?
Octreotide IV
What is the medical treatment of diarrhea alone?
Odansetron (Zofran®)—serotonin antagonist
How does the liver prevent carcinoid syndrome?
By degradation of serotonin and the other vasoactive peptides when the tumor drains into the portal vein
Why does carcinoid syndrome occur in some tumors and not in others?
Occurs when venous drainage from the tumor gains access to the systemic circulation by avoiding hepatic degradation of the vasoactive substances
What tumors can produce carcinoid syndrome?
- Liver metastases
- Retroperitoneal disease draining into paravertebral veins
- Primary tumor outside the GI tract, portal venous drainage e.g.,
- ovary
- testicular
- bronchus
What does the liver break down serotonin into?
5-hydroxyindoleacetic acid (5-HIAA)
What percentage of patients with a carcinoid have an elevated urine5-HIAA level?
50%
What are the associated diagnostic lab findings?
Elevated urine 5-HIAA as well as elevated urine and blood serotonin levels
What stimulation test can often elevate serotonin levels and causesymptoms of carcinoid syndrome?
Pentagastrin stimulation
How do you localize a GI carcinoid?
- Barium enema
- upper GI series with small bowel follow-through
- colonoscopy
- enteroscopy
- enteroclysis
- EGD
- radiology tests
What are the special radiologic (scintigraphy) localization tests?
- 131I-MIBG (131 metaiodobenzylguanidine)
- 111In-octreotide
- PET scan utilizing 11C-labeled HTP
