What are the main types of colonic polyps?
What are main histologic types of colonic polyps?
adenomatous (70%)- include tubular, villous, tubulovillous, and sessile serrated adenomas (these CAN develop into cancer)
non aenomatous (30%)- include hyperplastic, hamatomatous (Peutz-Jeghers syndrome), and Juvenile poylps (very low risk of developing into cancer)
What kind of polyp is this?
Non-adenomatous hyperplastic polyp
Describe Non-adenomatous hyperplastic polyps
These are the most common non-neoplastic polyp, usually diminutive in size, and located usually in the rectum or sigmoid colon (No malignant potential in small distal hyperplastic polyps)
How do hamartomatous polyps form?
Hamartomatous polyps occur sporadically or as components of various genetically determined or acquired syndromes (Peutz-Jeghers syndrome)
Describe Peurz-Jeghers Syndrome
This is an AD syndrome that presents around 11 y/o with multiple GI hamartomatous polyps in the small intestine and mucocutanoeus lesions on the buccal mucosa (below)
What mutation is common in Peutz-Jeghers Syndrome?
loss of function in gene STK11
Peutz-Jeghers syndrome is associated with a markedly increased risk of several malignancies. Name some.
•sex cord tumors of the testes;
•late childhood for gastric and small intestinal cancers; and the second and third decades of life for colon, pancreatic, breast, lung, ovarian, and uterine cancers
•Regular surveillance is recommended beginning at birth
What is this?
When and where do juvenile poylps most commonly occur?
In the rectum of children under 5 y/o (presents with rectal bleeding)
How do juvenile polyps form?
Morphogenesis incompletely understood. It has been proposed that mucosal hyperplasia is the initiating event
What are some complications of juvenile polyps?
•Intussusception, intestinal obstruction, or polyp prolapse (through the anal sphincter) may occur. Some malignant potential as well
How common is dysplastic transformation of a juvenile polyp?
Rare in sporadic polyps, but in contrast juvenile polyposis syndrome, 30% to 40% of patients with juvenile polyposis develop colonic adenocarcinoma by age 45
•Individuals with the autosomal dominant syndrome can have from 3 to as many as 100 hamartomatous polyps. A minority can undergo malignant transformation.
What is the most common mutation seen in juvenile polyps?
What are the risk factors for adenomatous polyp formation?
Age, abdominal obesity, male sex, and African American race are risk factors (Prevalence of 25-30 % at age 50)
Remember that adenomatous polyps can appear grossly as sessile, pedunculated, flat, or even depressed and
histologically can be tubular (80%), villous (5-15%), or mixed
Which types of adenomatous polyps have the most malignant potential?
villous is more likely than tubular due to typically being larger and Villous are usually sessile and more likely to infiltrate (larger= more likely to transform)
What is the difference between sessile serrated adenomas (SSAs) and hyperplastic polyps?
SSAs have some histological features of hyperplastic polyps but have malignant potential
Below: Narrow-band imaging to enhance vascular pattern to ID SSA polyp
T or F. SSAs are more common in the right/ascending colon
SSAs are most likely to have ____ or ____ mutations
MSI-H or BRAC
Tx for a polyp?
What is the most common GI malignancy?
What are the risk factors for CRC?
-age is most important
-fam Hx, chronic colitis, adenoma, previous colorectal neoplasia
-living in a developing country (high fat, low fiber diet)
-lack of physical activity
-red meat consumption
-cigs and alcohol
What things decrease the risk of CRC?
-multivitamins containing folic acid
-aspirin and other NSAIDs
-postmenopausal hormone use
-calcium and folate
-veggies, fruits, and fiber
•Incidence of CRC has declined by 30% in last decade in patients> age 50
Age is the most common risk factor for colon cancer*****
Need to start screening at age 50 (AA may be earlier-screen at age 45)
How is CRC in the right/ascending colon most likely to present?
The right colon has a larger lumen and thus is less likely to cause obstruction than the descending colon so the main presenting symptoms are most commonly:
-anemia (decreased hemoglobin)
-changed bowel habits
-rarely rectal bleeding (21%)
How is CRC in the left/descending colon most likely to present?
-abdominal pain (84%)
-changed bowel habits (86%)
rectal bleeding (44%)
How is CRC in the rectum most likely to present?
rectal bleeding (80%)
-abdominal pain (60%) and changed bowel habits
Bairum enemas arent used as much anymore