Carcinoid Tumour (22)

Question 1

What is an abscess?

Answer 1

• An abscess is a focal collection of pus caused by seeding of pyogenic organisms into a tissue or by secondary infections of necrotic foci.
• Abscess typically has a central, largely necrotic region rimmed by a layer of preserved neutrophils, with a surrounding zone of dilated vessels and fibroblast proliferation indicative of attempted repair.

Question 2

How do neutrophils migrate to the site of inflammation?

Answer 2

Neutrophils first roll, then become activated and adhere to endothelium, then transmigrate across the endothelium, pierce the basement membrane, and migrate toward chemoattractants emanating from the source of injury.

Question 3

What blood tests can identify inflammation?

Answer 3

• ESR and CRP
• White blood cell count

Question 4

What is a carcinoid tumor?

Answer 4

A carcinoid tumor is a slow-growing type of neuroendocrine tumor originating in the cells of the neuroendocrine system.

Question 5

Where is a carcinoid tumor most commonly found?

Answer 5

Small intestine, appendix (terminal third), and they can also be found in the rectum, stomach, and lung.

Question 6

What cells do carcinoid tumors arise from?

Answer 6

Carcinoid tumors arise from enterochromaffin (EC) cells (also known as Kulchitsky cells) in the crypts of Lieberkuhn.

Question 7

What does a carcinoid tumor release?

Answer 7

Notably, serotonin (5-HT), bradykinins, prostaglandins, tachykinins, substance P, and histamine.

Question 8

What are the clinical presentations of carcinoid tumors?

Answer 8

• Periodic abdominal pain
• Manifestations of carcinoid syndrome:
  
  • Cutaneous flushing
  • Diarrhea and malabsorption
  • Cardiac manifestations: Valvular heart lesions, fibrosis of the endocardium
  • Wheezing or asthma-like syndrome: Due to bronchial constriction

Question 9

How does a carcinoid tumor spread?

Answer 9

Cells produce a significant amount of beta-catenin, which enables the tumor cell adhesion, thus promoting metastasis.

Question 9

What is the most common metastatic site for carcinoid tumors?

Answer 9

The liver.

Question 10

Why do people with heavy metastasis in the liver have more symptoms than those with a primary tumor?

Answer 10

• Carcinoid tumors can overproduce substances such as serotonin that cause symptoms
  
  • Liver has enzymes that break down and neutralize these substances
    
    • Prevents them from reaching tissues where they can cause symptoms
  • Metastasis to the liver allows substances to more easily reach the bloodstream and tissues, causing symptoms

Question 11

What are the methods for diagnosing carcinoid syndrome?

Answer 11

-Chromogranin A (CgA) Testing in the blood (protein secreted from carcinoid tumor cells)

• 5-Hydroxyindoleacetic Acid (5-HIAA) Testing in 24 h urine (byproduct of serotonin)
• Pathological diagnosis: immunohistochemistry stains positive for chromogranin B.