A polyp is any protrusion or elevation of the intestinal surface into the lumen. A polyp can occur in esophagus, stomach, small intestine, gall bladder and Colon (most common). We will focus on colonic polyps since they have relevance in developing into colon cancer.
This means don’t necessary need polyp to become cancerous. HNPCC is also known as Warthin Lynch Syndrome. It is a defective DNA Mismatch Repair gene (MLH1, MSH2) causing Microsatellite instability (MSI). Patient with HNPCC less commonly form polyps than FAPs. HNPCC are more commonly right sided. Tumors may be multiple and mucinous in histology. Precursors can be: Hyperplastic Polyps, none, Sessile serrated adenoma.
FAP variants: (no screening recommendations)
Gardner Syndrome: Autosomal dominant predisposition characterized by FAP plus Multiple osteomas, Congenital hypertrophy of retinal epithelium, fibromatosis (desmoids tumors), epidermal cyst
Turcot Syndrome: is characterized by FAP plus CNS tumors like glioblastoma among others.
Familial Adenomatous Polyposis: (FAP)
Predispose mutation of a copy of APC gene on chromosome 5 (autosomal dominant)
Develop 1000s (minimum 100 to diagnose FAP) of polyps and by age 40 will develop invasive carcinoma (colorectal cancer).
Panproctocolectomy recommended (followed with ileo-rectal anastomosis)
Harmatomatous (Non-inflammatory Non-neoplastic Polyps) 2 types we will go through
If only one polyps called juvenile polyps. If multiple called Juvenile Polyposis Syndrome (JPS)
Sporadic one polyps (No malignant potential); JP syndrome (increase risk of malignancy)
Juvenile Polyps are also seen in PTEN mutation associated Syndromes: Cowden Syndrome and Dannayan-Ruvacalba-Riley Syndromes
Peutz Jegher Polyps (Autosomal dominant) – no extra screening
Also have sporadic and Syndromic forms like JPS.
Multiple polyps in whole GIT but mainly in small intestine, colon.
(freckles like) Melanotic Pigmentations in mucocutaneous areas (Lip, Perioral, Face, Genitalia, Palms)
See multiple harmatoartous polyps throughout small bowel and colon.
Arborizing network of smooth muscles extending into the polyps and surrounds glands
Glands are lined by non-dysplastic epithelium rich in goblet cells
Yes Malignant potential in colon ( slightly higher than general population get colon cancer: 10% vs 6-8%) but such patients are at risk of developing carcinomas of pancreas, lung, breast, ovary, uterus.
Removal of colonic adenomas is important for minimizing cancer risk and mortality. Hence it is important to screen for polyps and remove them before cancer develops. We have already covered how colonoscopy are essential to screening for colonic polyps/cancer.
The removal of polyps called polypectomy is important in management of polyps. Many techniques are used during colonoscopy to remove polyps including:
Snare Excision, Biopsy forceps, Simple fulguration, including with argon plasma coagulation, Saline assisted endoscopic mucosal resection, Endoscopic submucosal dissection.
Snare excision is the most commonly used method for polypectomy of polyps >5 to 10 mm. Lesions less than 5 mm are removed with either biopsy forceps or by snare polypectomy.