• Role of colonoscopy in the treatment of malignant polyps
• Pathology of malignant colorectal polyps
• Assessing the risk of residual disease post-polypectomy
• Surgical salvage of the high-risk polyp
• Staging & non-endoscopic surveillance of malignant
polyp
Endoscopist BEFORE Histopathologist
• Predict polyp histology by morphology – OPTICAL Bx
• Aim for en bloc resection – AVOID piece-meal
Endoscopist BEFORE Histopathologist
• Endoscopy reporting
Site – Right Vs left colon (splenic flexure)
Size – >35mm – 75% of carcinoma
Pedunculated / Sessile - Villous 15% risk of Ca
Morphology – irregular, ulcer, hard, broad stalk
Paris classification of appearance
Kudo classification of pit pattern
Laterally spreading lesion
Non-lifting sign
One-piece / Piecemeal
Benign / Malignant
Completeness of excision
Histopathologist
Malignant Colorectal Polyp
is a lesion in which neoplastic cells have invaded through
the muscularis mucosae into the submucosa.
pT1 adenocarcinoma
is defined as invasion into the submucosa but not into
the muscularis propria
Carcinoma in situ / intramucosal carcinoma - OBSOLETE
(High Grade Dysplasia)
Histopathologist
• Degree of differentiation
• Size – microscopic assessment is most accurate
• Level of invasion into polyp – Haggitt & Kikuchi
Histopathologist
• Depth of invasion into submucosa
Haggitt
Kikuchi
Histopathologist
• Degree of differentiation
• Size – microscopic assessment is most accurate
• Level of invasion into polyp – Haggitt & Kikuchi
• Resection margin ≤ 1mm is an involved margin
• LVI, tumour budding, cribriform histology
Histopathologist
• 2nd opinion due to interobserver variability
Degree of differentiation
LVI
Estimation of risk of residual disease
• Malignant polyp – Colorectal MDT
• Estimate the risk of residual disease
Technique of resection
Resection margin
Degree of differentiation
Depth of invasion – Haggitt and Kikuchi
LVI
Estimation of risk of residual disease
Surgery should be considered, provided that the patient
is fit enough to undergo such surgery where
•
resection margin is deemed to be involved (< 1 mm)
•
Haggitt Level 4 or Kikuchi sm3
•
Kikuchi sm1 or sm2 with adverse histology
•
Poorly differentiated – is unusual
Colon Vs Rectum differences
Estimation of risk of residual disease
Surgery should be considered, provided that the patient
is fit enough to undergo such surgery where
•
resection margin is deemed to be involved (< 1 mm)
•
Haggitt Level 4 or Kikuchi sm3
•
Kikuchi sm1 or sm2 with adverse histology
•
Poorly differentiated – is unusual
Lymphovascular invasion
Tumour budding
Cribriform
Mucinous
In isolation
NOT
High risk
Estimation of risk of residual disease
Surgical decision making in high-risk polyps
Fitness
Impact of morbidity
Life expectancy
Mortality
Patient wishes
Surgery if predicted op mortality (CR-POSSUM)
< risk of residual disease
It should be remembered that even in ‘high-risk polyps’, it is more
likely that the resected specimen will NOT contain any evidence of
residual disease at the polypectomy site or in draining lymph nodes.
Staging and surveillance - TNM
• T – Little data on use of MRI or EUS for residual disease
• N – MRI or EUS unreliable
(Not accurate enough to judge whether a visible
lymph node does NOT contain cancer)
• M – CTCAP
Staging and surveillance - TNM
Endorectal US should be performed on all rectal
polyp tumours prior to transanal or surgical excision
(good practice BUT no good evidence)