10mm以上鋸歯状病変の内視鏡診断―LHPとSSA/Pは同一病変か?

Magnifying Endoscopic Diagnosis in Large Serrated Lesion:LHP vs. SSA/P

要旨　2003年7月～2010年12月の間に内視鏡的に完全切除された10mm以上の鋸歯状病変220病変を，WHOの病理診断基準に基づきTSA，HP，SSA/Pに分類する見直し診断を行った．LHP（large hyperplastic polyp）に相当する病変は195病変であり，そのうちHPが77病変（39.5％），SSA/Pは118病変（60.5％）であり，現時点ではLHPはSSA/Pと同一病変ではないと言わざるをえない結果であったが，右半結腸のLHPに限ってはSSA/Pと同義とした臨床的取り扱いでよいものと考える．これら鋸歯状病変の内視鏡的特徴は，TSAは松毬様隆起（pine cone appearance）とIV_H型pit，SSA/PはHPに比べ，右半結腸に好発することや開大II型pitとIII_H型pit（fernlike pit）を伴う隆起成分の目立つ病変であることと考えられた．

　A total of 224 lesions endoscopically completely resected during the period between July, 2003 and December, 2010 were subjected to differential re-diagnosis according to the WHO criteria to determine how they were consistent with the criteria for TSA（traditional serrated adenomas）, HP（hyperplastic polyps）, and SSA/P（sessile serrated adenomas/polyps）. Of these, a total of 195 were found to be consistent with the WHO criteria for LHP（large hyperplastic polyps）. Additionally, of these LHP, a total of 77（39.4％）and 118（60.5％）were found to be consistent with the WHO criteria for HP and SSA/P, respectively. It was thus concluded that LHP and SSA/P constituted distinct pathological entities. Of these serrated lesions, endoscopically, TSA appeared to be characterized by their pinecone appearance as well as by IV_H-type pit patterns, while SSA/P appeared to occur more frequently in the right-sided colon than HP and were largely accounted for by protruded components associated with III_H-type（fernlike）pit patterns.