Episode three resolves the malignant polyp on one anatomic fact: lymphatics in the colon begin at the muscularis mucosae, so disease confined above it cannot metastasize while submucosal invasion opens the door to nodal spread. Intramucosal adenocarcinoma behaves as high-grade dysplasia and is cured by complete resection, which is why the word on the path report pulls toward unnecessary surgery. The Kikuchi and Haggitt systems describe depth, but the modern algorithm aggregates depth with tumor budding, differentiation, lymphovascular invasion, and margin status rather than acting on depth alone. Surveillance then calibrates the next exam to the worst lesion found, with the shortest interval winning when findings conflict and a separate six-month site check for piecemeal EMR of lesions twenty millimeters or larger. Topics covered Muscularis mucosae and metastatic potential Intramucosal adenocarcinoma versus true cancer Kikuchi and Haggitt depth systems Aggregating high-risk histologic features Tumor budding by ITBCC criteria USMSTF twenty twenty surveillance intervals Serrated surveillance intervals Piecemeal EMR site surveillance Key decisions Intramucosal adenocarcinoma is confined above the muscularis mucosae and behaves as high-grade dysplasia, so complete endoscopic resection is curative and surgery is unnecessary morbidity. Deep submucosal invasion alone, meaning Kikuchi sm three, Haggitt level four, or over one thousand microns, without other adverse features carries only about two and a half percent nodal risk, which can spare surgery in poor operative candidates. Four high-risk features drive surgical referral regardless of invasion depth: poor differentiation, lymphovascular invasion, high-grade tumor budding, and a positive margin under one millimeter. High-grade tumor budding by ITBCC is ten or more buds in a zero point seven eight five square millimeter hotspot, defined as single cells or clusters of up to four cells at the invasive front, and pushes the decision toward surgery. The three-year interval is the default short interval, triggered by any single high-risk feature such as five to ten adenomas, an adenoma ten millimeters or larger, villous histology, high-grade dysplasia, or a large or dysplastic sessile serrated lesion. More than ten adenomas at the index exam triggers one-year follow-up and evaluation for a hereditary syndrome, and when findings conflict the shortest interval always applies. Piecemeal EMR of any lesion twenty millimeters or larger gets a site check at six months, then one year, then resumption of standard intervals, because local recurrence runs fifteen to twenty percent without margin ablation. For the full chapter with MCQs, tables, and primary-guideline references, visit www.boardpearls.com. Questions or feedback: [email protected].

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“What did the council decide on item 42?” — answered with the speaker and the moment.

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