What areas should be targeted for biopsy in cases of gastrointestinal polyps?

Biopsy Sites for Gastrointestinal Polyps

For gastric polyps, resect or biopsy the polyp itself (preferably complete resection of the largest polyp if multiple), and obtain biopsies from the surrounding non-polypoid gastric mucosa to assess for H. pylori, gastric atrophy, and intestinal metaplasia using the updated Sydney System protocol. 1

Gastric Polyp Biopsy Strategy

Direct Polyp Sampling

• Complete resection is preferred over biopsy for definitive histologic diagnosis, particularly for solitary polyps, as histologic features may be patchy within lesions 1
• If multiple polyps are present, resect the largest polyp(s) and take representative samples from remaining polyps 1
• For fundic gland polyps (FGPs): targeted biopsies are acceptable when excision is not undertaken, but excision is required if polyps are >1 cm, located in the antrum, ulcerated, or have unusual appearance 1
• For hyperplastic polyps >1 cm or pedunculated morphology: complete resection is mandatory due to dysplasia risk of 1.9-19% 1, 2
• For adenomatous polyps: en bloc excision with endoscopic submucosal dissection (ESD) is advisable for sessile polyps >15 mm due to high risk of invasive neoplasia 1

Surrounding Mucosa Biopsies (Updated Sydney System Protocol)

Obtain at least 5 biopsies from specific anatomic locations to assess for synchronous neoplasia, gastric atrophy, intestinal metaplasia, and H. pylori: 1

• 2 biopsies from the antrum: within 2-3 cm from pylorus, from both lesser and greater curvature 1
• 1 biopsy from the incisura angularis 1
• 2 biopsies from the body: one from lesser curvature (4 cm proximal from the angle) and one from greater curvature (8 cm distal to cardia) 1

Critical rationale: Hyperplastic polyps have 6% synchronous neoplasia risk, and adenomatous polyps have up to 30% coexistent gastric adenocarcinoma 1, 2. Separate labeling of antrum and body specimens allows assessment of extent, severity, and etiology of gastric atrophy and intestinal metaplasia 1

Gastric Ulcer Biopsy Protocol

If gastric ulcer biopsies are performed, take specimens from both the base and edges of the ulcer, plus biopsy the remainder of the stomach for H. pylori as described above 1

Colorectal Polyp Biopsy Strategy

Standard Approach: Resection Without Adjacent Biopsies

For colorectal polyps in non-IBD patients, resect the polyp itself without biopsies of surrounding flat mucosa 3, 4

• Cold snare polypectomy is recommended for all polyps <10 mm 4
• Hot snare polypectomy for pedunculated lesions >10 mm 4
• Include a 1-to-several millimeter rim of normal tissue around the polyp during resection 4

IBD-Specific Modifications

In inflammatory bowel disease patients, the approach differs significantly:

• Targeted biopsies should be performed where mucosal findings are suspicious for dysplasia or inexplicably different from surrounding mucosa 1
• Endoscopic resection is preferred to biopsies when lesions are clearly demarcated without stigmata of invasive cancer or submucosal fibrosis 1
• Mucosal biopsies surrounding a resected lesion are NOT required unless there are concerns about resection completeness 1

Evidence supporting this approach: Studies demonstrate that peri-polyp biopsies in IBD have negligible yield (0.7% dysplasia detection, 0% unsuspected dysplasia with 95% CI 0-1.6%), and dysplasia in adjacent biopsies does not predict subsequent neoplasia risk 5, 6. The grade of dysplasia in the polyp itself is the only predictor of subsequent advanced neoplasia 5

When Malignancy is Suspected

If clear evidence of submucosal invasive cancer is present: 1, 4

• Perform limited cold forceps biopsy of the most suspicious areas to confirm histology 1
• Tattoo the lesion at 2-3 locations, 3-5 cm distal to the lesion (or in line with and on opposite lumen wall if for surgical localization) 1, 3
• Refer for surgical evaluation 1, 4

Common Pitfalls to Avoid

• Do not assume all antral polyps are hyperplastic: adenomatous polyps have 30% synchronous gastric adenocarcinoma rate and 50% contain cancer when >2 cm 2
• Do not delay resection of large gastric polyps (>3 cm) for H. pylori eradication—these must be resected immediately due to high malignancy risk 2
• Do not routinely biopsy peri-polyp flat mucosa in IBD unless endoscopically abnormal—this practice has been abandoned based on negligible diagnostic yield 5, 6
• Do not cut large pedunculated specimens to facilitate removal through the suction channel, as this prevents proper pathologic assessment 3