A 58-year-old Indian woman undergoes screening colonoscopy and a 12 mm flat lesion with indistinct borders and a mucus cap is identified in the right colon. Biopsies confirm a sessile serrated lesion (SSL) without dysplasia. The endoscopist performs the procedure marked **A** in the diagram — submucosal injection with indigo carmine followed by snare polypectomy with complete resection. Which of the following best describes the rationale for this management approach and the subsequent surveillance interval?
A. Complete endoscopic resection with submucosal injection reduces perforation risk and enables histopathologic assessment; 3-year surveillance interval is recommended due to SSL size ≥10 mm
B. Submucosal injection is unnecessary for SSLs; observation alone with repeat colonoscopy at 10 years is standard care
C. Endoscopic mucosal resection is contraindicated in right-sided lesions; surgical resection should be performed immediately
D. Piecemeal resection without submucosal injection is preferred to minimize mucosal trauma; 6-month surveillance is mandatory
Explanation
Why option 1 is correct
Sessile serrated lesions (SSLs) are flat, often-missed precursor lesions with indistinct borders that follow the serrated carcinogenic pathway — distinct from conventional adenomas. They have a faster precursor-to-cancer trajectory and contribute disproportionately to interval cancers. Complete endoscopic resection is mandatory. For lesions ≥10 mm, endoscopic mucosal resection (EMR) with submucosal injection of dilute indigo carmine (or saline ± epinephrine) is the standard technique because it lifts the lesion away from the muscularis propria, reducing perforation risk and enabling complete histopathologic assessment of margins and dysplasia. According to the US Multi-Society Task Force 2020 Surveillance Guidelines, SSLs ≥10 mm or with dysplasia require 3-year surveillance intervals to detect any residual disease or metachronous lesions early, given their aggressive biology. This directly addresses the clinical anchor: complete resection with submucosal injection is the evidence-based standard for lesions of this size and location.
Why each distractor is wrong
Option 2: Observation without resection is inappropriate and dangerous. SSLs are precursor lesions with malignant potential; complete endoscopic resection is mandatory per all major guidelines. Submucosal injection is essential for safe, complete resection of lesions ≥10 mm. A 10-year surveillance interval is far too long for a 12 mm SSL.
Option 3: Endoscopic mucosal resection is not contraindicated in right-sided lesions; in fact, the right colon is the predominant location for SSLs. Surgical resection is reserved for endoscopically unresectable lesions or those with invasive carcinoma and deep submucosal invasion — not for a resectable 12 mm SSL.
Option 4: Piecemeal resection (fragmented removal) is associated with higher recurrence and incomplete histologic assessment. Submucosal injection is essential, not unnecessary. While piecemeal resection does warrant 6-month to 1-year surveillance, this is not the preferred technique for a lesion of this size that can be resected en bloc with EMR.
High-YieldNEET PG
Sessile serrated lesions ≥10 mm require endoscopic mucosal resection with submucosal injection for complete en bloc resection and 3-year surveillance; they are flat, right-sided, easily missed, and follow an aggressive serrated carcinogenic pathway distinct from conventional adenomas.
US Multi-Society Task Force Surveillance Guidelines 2020; Sleisenger 11th ed
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