Polyps

Question 1

What is a polyp?

Answer 1

Protrusion of tissue into lumen above surrounding intestinal mucosa

Question 2

How are colorectal polyps classified?

Answer 2

• by their morphologic/endoscopic appearance (Paris classification)
  
  • pedunculated, sessile, flat, depressed
• by histology
  
  • non-neoplastic
    
    • hyperplastic
    • inflammatory
      
      • inflammatory pseudopolyps
      • prolapse-type inflammatory polyps
    • hamartomatous
      
      • juvenile polyps
      • Peutz-Jeghers polyps
      • Conkhite-Canada syndrome
      • PTEN hamartoma tumour syndrome
  • neoplastic
    
    • serrated polyps
      
      • (hyperplastic polyps are serrated but non-neoplastic)
      • TSAs
      • SSA/Ps +/- dysplasia
    • traditional adenomatous polyps
      
      • tubular, tubulovillous or villous +/- dysplasia
    • malignant polyps

Question 3

What are inflammatory pseudopolyps?

Answer 3

Non-neoplastic intraluminal projections consisting of epithelial and stromal components plus inflammatory cells. They are irregularly shaped islands of residual intact mucosa that are the result of mucosal ulceration and regeneration that occurs in response to localised or diffuse inflammation (eg UC or Crohn’s).

Question 4

What are prolapse-type inflammatory polyps?

Answer 4

Result from traction, distortion & twisting of mucosa caused by peristalsis-induced trauma –> localised ischaemia & lamina propria fibrosis. Eg seen in rectal prolapse.

Question 5

What are hamartomatous polyps?

Answer 5

Made up of tissue elements normally found at that site but growing in a disorganised mass.

May be sporadic but more commonly seen in genetic syndromes eg Peutz-Jeghers, juvenile polyposis and PTEN hamartoma syndrome.

Sporadic juvenile polyps of colon occur in up to 2% of chidlren <10yrs - usu solitary, not assoc w increased CRC (isolated ones most common in rectosigmoid).

Juvenile polyposis syndrome = autosomal dominant condition characterised by multiple hamartomatous polyps throughout GI tract - at increased risk for colorectal & gastric cancer.

PTEN hamartoma tumour syndrome = primarily composed of Cowden & BRRS syndrome; due to mutation in PTEN gene.

Question 6

What are hyperplastic polyps?

Answer 6

A form of serrated polyp. They are the most common type of non-neoplastic polyp in the colon; don’t appear to have malignant potential but may be associated with an increased risk of proximal neoplasia. Histologically they have a characteristic ‘saw tooth’ pattern and can be difficult to distinguish from SSA/P.

Question 7

What are sessile serrated adenomas?

Answer 7

• A form of serrated polyp
• More prevalent in the proximal colon
• Have a smooth surface sometimes with a ‘cloud-like’ appearance, often flat/sessile & may be covered with mucus
• May acquire dysplasia

SSPs, particularly those with dysplasia, are considered the likely precursers of sporadic MSI-H colon ca through a molecular pathway characterised by a high frequency of methylation of some CpG islands (CIMP-positive) - may result in hypermethylation of the promoter region of MMR MLH1 & silencing of gene expression. Activation of the BRAF oncogene (BRAF V600E mutation) = also a feature of SSA/Ps, as well as many hyperplastic polyps

Question 8

What are traditional serrated polyps?

Answer 8

• A form of serrated polyp
• More prevalent in the rectosigmoid colon
• May be flat or pedunculated
• Have diffuse but often mild dysplasia

Question 9

What is serrated polyposis syndrome?

Answer 9

A rare condition characterised by multiple large and/or proximal serrated polyps. These patients carry an increased risk of CRC; the lifetime risk is unknown but the 5year risk while under surveillance is 1%.

Diagnosed by the WHO criteria:

1. At least 5 serrated polyps proximal to the rectum all ≥5mm, with at least 2 ≥10mm

OR

2. >20 serrated polyps of any size but distributed throughout the large bowel, with ≥5 proximal to the rectum

(Any histological subtype is included and the diagnosis may require >1 colonoscopy; polyp count cumulative over time.)

Question 10

How common are adenomatous polyps and what are the risk factors for these?

What are some endoscopic features suggestive of invasive cancer?

Answer 10

• Commonest type of colonic polyp - account for > 2/3
• 25% by age 50, 50% by age 70
• Risk factors: increasing age, BMI, lack of exercise, male

Only a small minoirty (≤5% over 7-10yrs) progress to ca but risk is higher if HGD, ≥10mm or villous component.

Endoscopic features suggestive of invasive carcinoma include friability, induration and ulceration.

Question 11

What is the Paris classification?

Answer 11

The Paris classification of superficial gastrointestinal neoplastic lesions:

• 0-I Polypoid:
  
  • 0-Ip: protruded, pedunculated
  • 0-Is: protruded, sessile
• 0-II Nonpolypoid:
  
  • 0-IIa: slightly elevated
  • 0-IIb: flat
  • 0-IIc: slightly depressed
• 0-III Excavated

Question 12

What are the different histological types of adenomatous polyps?

Answer 12

Advanced adenoma = ≥10mm, villous component or HGD

Tubular adenoma = >80% adenomas, need ≥75% tubular component (branching, adenomatous epithelium)

Villous adenoma = 5-15% adenomas, need ≥75% villous component (long glands extending straight down from surface to centre of polyp)

Tubulovillous = 5-15%, have 25-75% villous features

Some degree of dysplasia in all polyps:

• LGD
• HGD/intraepithelial carcinoma (no invasion through BM)
• carcinoma in situ (invasion into LP but don’t penetrate MM)
• invasive adenocarcinoma (extends through MM and beyond)

Question 13

What is the endoscopic management of polyps?

Answer 13

Adenomatous polyps

• if ≤2mm may be completely removed w biopsy forceps
• otherwise snare +/- electrocautery or advanced techniques (EMR/ESD)
• large sessile ones often need piecemeal resection
• otherwise surgery
• pedunculated polyps w features of deep submucosal invasion - polypectomy with en bloc resecton
• nonpedunculated polyps w features of deep submucosal invasion - biopsy area of surface feature disruption, tattoo if polyps not at or near caecum & refer for surgical mx
  
  • these polyps should be resected en bloc rather than piecemeal

Serrated polyps ≥5mm should be completely resected

Question 14

What are the categories of polyp risk?

Answer 14

• Average risk polyps
  
  • Conventional adenomas
    
    • tubular adenoma <10mm
  • Serrated polyps
    
    • SSA/P <10mm
    • Hyperplastic polyp ≥10mm (f/u as high risk polyp if concern re distinguishing from SSP)
• High risk polyps
  
  • Conventional adenomas (these are advanced adenomas)
    
    • adenoma ≥10mm
    • adenoma w villous or tublovillous histo (>25% villous histo)
    • adenoma w HGD
  • Serrated polyps
    
    • SSA/P ≥10mm
    • SSA/P w HGD
    • TSA
    • Serrated adenoma, unclassified

Question 15

What is the recommended follow-up after polyp excision in the absence of a known familial disorder/family history concerns?

Answer 15

• after piecemeal resection of polyps ≥20mm, site should be checked within 2-6mo then additional colonoscopy after further 12mo
  
  • once no recurrence confirmed, surveillance after further 3yrs; then need for further durveillance determined in accordance w this update & individual virus factors
• no surveillance for hyperplastic polyps ≤10mm unless meets criteria for serrated polyposis syndrome

Surveillance intervals:

• Adenomas
  
  • ​1 year:
    
    • ≥10 adenomas (consider ref to NZFGCS)
  • 3yrs:
    
    • 5-9 adenomas <10mm
    • 1 advanced adenoma
  • 5yrs:
    
    • 3-4 adenomas <10mm
  • 10yrs or NZBSP (whichever first)
    
    • 1-2 adenomas <10mm
• Serrated polyps
  
  • 1year:
    
    • SPS - initial interval after polyp clearance (consider ref to NZFGCS)
  • 3yrs:
    
    • ≥5 SSA/P <10mm
    • SSA/P ≥10mm
    • SSA/P w dysplasia
    • TSA
  • 5yrs
    
    • 1-4 SSA/P <10mm
    • HP ≥10mm (3yrs if concern re differentiating from SSA/P)

If >75yrs, or significant comorbidities, consider risks & benefits - only survey if >10yrs life expectancy

Question 16

What are the factors involved in a high quality colonoscopy and polypectomy?

Answer 16

High quality colonoscopy

• Credentialed colonoscopist
• Bowel prep sufficient - BBPS on withdrawal ≥6, w no single segment score <2
• Photo documentation of caecal intubation & retroflexion into rectum

High quality polypectomy

• Complete removal of all neoplastic tissue
• Measure polyp size using width of snare
• Assess morphology of polyp with PARIS classification + pit pattern with virtual or chromoendoscopy
• Removal of polyps assessed to be difficult (size, momrphology, site, access criteria), including those >2cm, consider deferring for appropriately experienced & skilled endoscopy

Question 17

How is Bowel Prep Scored?

Answer 17

Boston Bowel Prep Scale

• large bowel divided into 3 sections: right, transverse (incl flexures), left with rectum
• each scored from 0-3
• 0 = unprepared colon segment with mucosa not seen due to solid stool that can’t be cleared
• 1 = portion of mucosa of colon seen, but other areas of colon segment not well seen due to staining, residual stool and/or opaque liquid
• 2 = minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well
• 3 = entire mucosa of colon segment seen well w no residual staining, small fragments of stool or opaque liquid

Total score 0-9

Question 18

What are the referral criteria to the NZ Familial GI Cancer Service on the basis of polyps?

Answer 18

Serrated polyposis syndrome and one of:

• age <50
• personal hx CRC
• 1st degree relative w CRC or SPS dx age <50yrs
• >20 polyps & 2 >10mm
• presence of serrated lesions w dysplasia

Mutiple adenoma; refer if

• ≥10 adenomas at one time or within a 2yr period (if >70 must have ≥1 advanced adenoma)
• ≥5 advanced adenomas at one time or within a 2yr period
• 20 cumulative adenomas
• 10 cumulative adenomas if pt ≤30

Question 19

How are malignant polyps classified?

Answer 19

Invasive cancer in a polyp = invasion through the muscularis mucosa into the submucosa (T1) - has the potential to metastasise to LNs & distant sites (nb T2 = treated as normal CRC)

Haggitt classification = for pedunculated polyps

• level 1: ca limited to head of polyp
• level 2: ca invades to level of neck of polyp
• level 3: ca invades any part of the stalk
• level 4: ca invades into the submucosa of the bowel wall below the level of the stalk
• risk of residual disease is <1% for levels 1,2,3 and 20% for level 4
• a sessile adenoma has an absent stalk so by definition sessile polyps with invasion through MM = level 4, same risk

Kikuchi classificaton = for sessile polyps

• characterised risks in full-thickness rectal biopsies taken at transanal surgery
• Sm1 = invasion into upper 1/3 of submucosa, 2% risk nodal met
• Sm2 = invasion into middle 1/3 of submucosa, 8% risk nodal met
• Sm3 = invasion into lower third submucosa, 23% risk nodal met
• Sm2

Question 20

Other than the Haggitt or Kikuchi classification, what are other histological features that increase the risk of residual disease after resection of a malignant polyp?

Answer 20

• margin <1mm (same significance as a positive margin; 1-2mm also not ideal but low risk (5%) of residual disease)
• poor differentiation
• LVI
• tumour budding
• also recognise limitations assoc w piecemeal EMR specimens; unless all submucosa included, predictions are unreliable
• no need for resection if none of above present and
  
  • depth of invasion below muscularis mucosae of ≤1mm
  • Haggit 1-3 or Kikuchi Sm2 or Sm3

NB even when dealing with malignant polyps with the highest risk of residual disease, 70-90% of pts won’t have ca within the specimen

Question 21

What is a colorectal polyp?

Answer 21

Protrusion of tissue into lumen above surrounding intestinal mucosa. Usually asymptomatic but may bleed or cause obstructive sx, and some are prescursors for cancer

Question 22

How are colonic polyps classified

Answer 22

Endoscopic appearance: sessile vs pedunculated

Histo
- Non-neoplastic
- Hyperplastic
- Inflammatory
- Inflammatory pseudopolyp
- Prolapse-type inflammatory polyp
- Hamartomatous
- Sporadic
- Related to a genetic syndrome eg
Juvenile polyposis, Peutz-Jeghers,
Cronkhite-Canada syndrome, PTEN
hamartoma tumour syndrome
- Neoplastic
- Serrated polyps
- (hyperplastic polyps grouped w
these but non-neoplastic)
- TSAs
- SSPs – w & w/o cytological
dysplasia
- Conventional adenomatous polyps
- Malignant polyps

Question 23

Classify polyps into average and high risk from a surveillance perspective

Answer 23

Average risk

• Conventional adenomas: tubular, <10mm
• Serrated adenomas: hyperplastic polyp ≥10mm, SSP/A <10mm

High risk

• Conventional adenomas: ≥10mm, tubulovillous or villous, HGD (advanced adenoma)
• Serrated adenomas: SSA/P ≥10mm or with dysplasia, TSA, serrated adenoma unclassified

Question 24

Relate malignancy risk to polyp size

Answer 24

Polyps <1cm: <1% risk malignancy; polyps 1-2cm: 10% risk; polyps >2cm: 40% risk

Question 25

State Amsterdam II criteria and its purpose

Answer 25

- Modified from the Amsterdam I criteria to identify patients at risk of a hereditary cancer syndrome - 50% of families that meet the Amsterdam criteria have Lynch, and 50% of families with Lynch meet Amsterdam criteria (ie Amsterdam criteria alone not enough to dx Lynch; also need tumour analysis and/or genetic testing - ≥3 relatives w Lynch-associated cancer, at least 1 of whom should be a first degree relative of the other two - ≥2 successive generations affected - ≥1 cancer should be dx before age 50 - FAP should be excluded - Tumours should be verified on pathology

Question 26

What are the cancers associated with Lynch syndrome and their frequency

Answer 26

- Large bowel 40%F, 70%M - Endometrium 30-70% of F - Stomach 5-10% - Ovary 5-10% of F - Urothelium – renal pelvis, ureter, bladder 5% - Other (SB, panc, brain) \<5%

Question 27

What are the Bethesda criteria as they relate to Lynch syndrome

Answer 27

A means of identifying those that may have Lynch syndrome -criteria to determine whether tumour tissue should be tested for MSI BET H – histopath features indicative of MSI in someone dx w CRC \<60 (presence of tumour-infiltrating lymphocytes, Crohns-like lymphocytic reaction, mucinous/signet-ring cell differentiation, or medullary growth pattern E – extra lynch cancers – multiple colorectal or other Lynch-assoc tumours either synchronous or metachronous regardless of age S – single - ≥1 1st degree rel w Lynch ca ≤50 D – double - ≥2 1st or 2nd degree rels w Lynch ca at any age A – age – CRC \<50yrs (Used to use Bethesda criteria more; now most CRCs will be stained w IHC as a screening test looking for lossof MMR proteins on outside of cells; if missing, then look for MSI which is the phenotypic defect seen in Lynch

Question 28

What is the management of Serrated polyposis syndrome?

Answer 28

- Clearance of all SSLs & conventional adenomas - Surveillance colonoscopy; first colonoscopy after polyp clearance at 1 year then 1-2yearly depending on findings - Consider aspirin to reduce the risk of serrated polyps from age 50 - Total colectomy not recommended unless number & size of polyps makes it impossible to remove all polyps ≥5mm in which case colectomy & IRA should be considered - If CRC dx in a pt w SPS, option of partial colectomy & debulking of any remaining colorectal polyps OR total colectomy to avoid frequent colonoscopy depending on pt preference

Question 29

Describe the classification of polypoidal pit patterns on magnified NBI colonoscopy.

Answer 29

Type I and II are considered benign changes (e.g., normal, hyperplastic, inflammatory polyps), whereas pit pattern classes III-V are considered to show neoplastic and malignant changes.

Question 30

Describe the classification and relative frequency of colonic polyps

Answer 30

1. **_Neoplastic polyps_** * Adenomas _(two thirds of all colonic polyps)_ * Adenocarcinomas (infrequent) 2. **_Hyperplastic_** * _Most common non-neoplastic polyp_ * Serrated (saw-tooth) pattern * May occur in context of hyperplastic polyposis syndrome\* 3. **_Inflammatory pseudopolyps_** * Associated with inflammatory conditions of the bowel * Non-neoplastic 4. **_Hamartomatous polyps_** 1. Juvenile Polyps * Remove if symptomatic (often bleed) * If part of Familial Juvenile Polyposis syndrome - increased risk Ca. 2. Peutz-Jeghers * Adenomatous change occurs in ~5% of these so resect 3. Cronkhite-Canada Syndrome * Rare, non-familial; alopecia, cutaneous hyperpigmentation, nail changes * Polyps often bleed 4. PTEN syndromes (Cowden, Bannayan-Riley-Ruvalcaba syndrome)