Path Notes: Intestinal Polyps: Non-Neoplastic Polyps********

Question 1

What are intestinal polyps? What is their morphology?

Answer 1

Intestinal polyps are masses that extend into the intestinal lumen.

Morphologically, they are:

1. Sessile (no stalk)
2. Pedunculated (with stalk)

Question 2

What are the two pathological types of intestinal polyps? (Just name them)

Answer 2

1. Non-neoplastic
   Can arise from abnormal maturation, inflammation or architecture. There is no malignant potential per se.
2. Neoplastic

Question 3

What are some examples of Non-neoplastic Intestinal polyps, describe them>

Answer 3

Non-Neoplastic polyps can arise from abnormal maturation, inflammation or architecture

Examples:
1. Inflammatory Polyp = May form from chronic cycles of injury and healing

2. Hyperplastic Polyp = Associated with changes in cell turnover - decreased epithelial cell turnover leads to accumulation of mature cells on surface
3. Hamartamotous Polyp = Tumour-like growth composed of mature tissue which is normal to the area in which the polyp has arisen. E.g. of this is Juvelile Polyp (which can be sporadic or syndromic). Or Peutz-Jeghers Polyp (rare AD syndrome)

Question 4

What are Neoplastic Polyps?

Answer 4

A common type of neoplastic polyp is an adenoma (adenomatous polyp). These can progress to cancer

Question 5

Describe Hyperplastic Polyps:

Answer 5

Account for 90% of non-neoplastic intestinal polyps

Unknown aetiology

Typically rectosigmoid

Very common

Associated with changes in cell turnover: decreased epithelial cell turnover leads to an accumulation of mature cells on the surface.

Question 6

Describe Hamartomatous Polyps (not including subtypes)

Answer 6

Generally have no malignant potential - non-neoplastic intestinal polyp

80% of harmatomatous polyps develop in the rectum, but they may be scattered

Question 7

What are the three subtypes of Hamatomatous Polyps?

Answer 7

1. Juvenile Polyps (sporadic type)
2. Juvenile Polyposis (syndrome)
3. Peutz-Jeghers Polyps

Question 8

Describe Juvenile Polyps - sporadic type. Epidemiology, macro features

Answer 8

AKA retention polyps

Involves hamatomatous malformation (growth that resembles a tumour that is non-neoplastic) of the mucosal epithelium and lamina propria

Typically occurs in those <5yo

Mostly occur in the rectum

Macroscopically:
1-3cm diameter
Rounded smooth or slightly lobulated
Stalks up to 2cm long
The lamina propria bulk of the polyp contains cystically dilated glands

Question 9

Describe Juvenile Polyposis syndrome. Epidemiology and maco features

Answer 9

Autosomal Dominant syndrome

Sometimes associated with SMAD / DZPC4 gene mutations - an intermediate signalling by TGF-B

Invovles multiple juvenile polyps: 50-100

Associated with increased risk of adenocarcinoma*

Macroscopically:
1-3 cm diameter
Rounded smooth or slightly lobulated
Stalks up to 2 cm long
Lamina propria bulk of the polyp contains cystically dilated glands

Question 10

Describe Peutz-Jhegers Polyps: Epidemiology / Pathological features

Answer 10

Rare autosomal dominant syndrome

Mutation of the LKB1 / STK11 gene of chromosome 19

LKB1 / STK11 is a kinase that regulates cell polarisation, growth and metabolism

Involves multiple polyps scattered throughout entire GIT - 25% in stomach, 30% in colon, 100% in small bowel

Melanotic mucosal and cutaneous pigmentation around the lips, oral mucosa, face, genitalia, palmar surfaces of the hands

The polyps have no malignant potential, but GIT adenocarcinoma can arise independently of the Peutz-Jhegers polyps.

Generally, people with Peutz-Jhegers have an increased risk of cancer of colon, pancreas, breast, lung, ovary, testes and uterus

Question 11

Peuts-Jhagers Polyps: Macro and Micro features

Answer 11

Macroscopically:

1. Polyps are large and pedunculated
2. Have firm, lobulated contour

Microscopically:

1. Network of of connective tissue and well developed smooth muscle extends into the polyp
2. This network also surrounds normal glands