Sessile: Kikuchi classification sm1-3: level of submucosa depth by thirds. Risk of nodal mets 2, 8 and 23% respectively.
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Sm1 local excision adequate
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Sm2/3 not recommended for local excision
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A major drawback of this classification scheme is that it requires either the specimen to contain a portion of the muscularis propria, or for the to estimate where this margin might have been, which also puts the patient at a greater risk of perforation.
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Others have suggested that invasion of more than 1 mm into the submucosa is associated with lymph node metastasis.
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Using 1 mm of submucosal invasion as a cutoff limits some of the subjective assessment required with other methods, while potentially still identifying patients who are adequately treated with polypectomy.