Colorectal

Question 1

Pathophysiology of UC

Answer 1

• chronic IBD
• the exact cause of UC is not yet fully understood
• but it is thought to arise due to a combination of genetic, environmental, and immunological factors
• an abnormal immune response directed towards the intestinal lining.
• Immune dysregulation: an inappropriate and exaggerated immune response within the intestinal mucosa. It is believed that a combination of genetic susceptibility and environmental triggers leads to an overactive immune response against normal gut bacteria. This response involves both innate and adaptive immunity, including the recruitment and activation of various immune cells such as T lymphocytes, B lymphocytes, neutrophils, and macrophages.
• Intestinal barrier dysfunction: In ulcerative colitis, there is a disruption of the intestinal barrier, which normally separates the gut contents from the underlying tissues. This disruption allows the infiltration of inflammatory cells and antigens into the intestinal wall. It also impairs the absorption of water and electrolytes, leading to diarrhea.
• Inflammation and mucosal damage: The influx of immune cells into the intestinal mucosa leads to chronic inflammation. The release of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6), contributes to the recruitment and activation of additional immune cells, perpetuating the inflammatory process. The chronic inflammation causes damage to the colonic mucosa, leading to the characteristic features of UC, including ulceration, edema, and bleeding.
• Crypt abscesses and tissue damage: Crypt abscesses, which are collections of inflammatory cells within the intestinal crypts, are commonly seen in ulcerative colitis. These abscesses can contribute to the destruction of the colonic mucosa and the formation of ulcers. Over time, repeated cycles of inflammation and healing result in architectural changes, loss of crypts, and tissue scarring.
• Systemic manifestations: Ulcerative colitis is not limited to the colon and rectum, as it can also cause systemic manifestations. These may include joint pain, skin rashes, ocular inflammation, and liver disorders (e.g., primary sclerosing cholangitis).

Question 2

What is CEA?

Answer 2

• Carcinoembryonic antigen.
• it is a glycoprotein involved in cell adhesions.
• used as tumour markers for colon cancer, cholangiocarcinoma and medullary thyroid cancer.
• can be raised in smokers, IBD, alcoholic cirrhosis.