inverted SSA/Pの臨床病理学的特徴

Clinicopathological Features of Inverted Sessile Serrated Adenoma/Polyp of the Colon

要旨●大腸inverted SSA/Pの臨床病理学的特徴を明らかにするために，拡大内視鏡検査を施行し内視鏡的に摘除した7症例8病変を対象とし，遡及的に検討した．inverted SSA/Pの平均病変径は12.4±4.6mm，病変部位は右側大腸5病変，左側大腸3病変であった．肉眼型は粘液貯留を伴った表面陥凹型が5病変と最も多く，次いで表面型が2病変，隆起型が1病変であった．拡大観察ではII型pitは全例でみられ，開II型pitは6病変に，シダの葉状所見は4病変にみられた．NBI拡大観察においては，varicose microvascular vesselが6病変に，expanded crypt openingsが5病変に観察された．病理組織学的には全例で粘膜筋板の欠損を認め，recent hemorrhageは左側大腸の病変で多く認められた．以上より，通常観察および拡大内視鏡観察はinverted SSA/Pの診断に有用であると結論した．

　Objective : This investigation aimed to clarify the clinicopathological features of inverted SSA/P（sessile serrated adenoma/polyp）of the colon.

　Methods : We identified eight inverted SSA/Ps that were endoscopically resected at our institution, and their colonoscopic findings were retrospectively investigated.

　Results : The inverted SSA/Ps were predominantly right-sided and revealed a flat-elevated configuration with a central depression. Using Kudo's criteria, magnifying chromoendoscopy revealed type II pit patterns in all lesions and type II open-shape pit patterns in six lesions. Narrow band imaging revealed numerous varicose microvascular vessels or expanded crypt openings.

　Conclusions : Conventional and magnifying endoscopies appear to be invaluable for the diagnosis of inverted SSA/P.