大腸鋸歯状病変の病理診断

Pathological Diagnosis of Colorectal Serrated Lesions

要旨●大腸鋸歯状病変は，古くは非腫瘍性病変としてのhyperplastic（metaplastic）polypのみであったが，その後さまざまな鋸歯状病変が提唱され，現在ではtraditional serrated adenoma（TSA），sessile serrated adenoma/polyp（SSA/P）〔その後sessile serrated lesion（SSL）に名称変更〕，serrated tubulovillous adenoma（sTVA），mucin rich variant of traditional serrated adenoma（MR-TSA），superficially serrated adenoma（SuSA），serrated adenocarcinoma（SAC）という名称の病変が存在する．これらはしばしば混在し，中間的な病変も存在するので，その分類に苦慮することがある．それぞれの臨床的意義と本質的な病理組織学的特徴を十分理解して分類する必要がある．

　In previous studies, colorectal serrated lesions have been limited to a hyperplastic（metaplastic）polyp as a nonneoplastic lesion. In subsequent studies, various serrated lesions have been proposed：traditional serrated adenoma, sessile serrated adenoma/polyp（later renamed as sessile serrated lesion）, serrated tubulovillous adenoma, mucin-rich variant of traditional serrated adenoma, superficially serrated adenoma, and serrated adenocarcinoma. These lesions often coexist, along with the presence of intermediate lesions, making classification challenging. Therefore, it is necessary to understand the clinical significance of each lesion and their essential histopathological characteristics to facilitate classification.