大腸鋸歯状病変の病理診断基準と課題—WHO2019を踏まえて

Pathological Diagnostic Criteria and Issues with Serrated Lesions of the Colorectum Based on WHO 2019 Criteria

要旨●近年，大腸癌の新たな発癌経路として大腸鋸歯状病変を前駆病変とするserrated pathwayが提唱され，国際的に注目されている．しかし，大腸鋸歯状病変は病理組織学的，分子生物学的に多様であり，いまだ十分な病理診断基準の確立には至っていない．さらに，2019年には消化器腫瘍領域のWHO分類が9年ぶりに改訂され，大腸鋸歯状病変における分類と病理診断基準についても変更が加えられた．大腸鋸歯状病変の病理診断基準の確立のためには病変の本質を理解し，その本質を表す組織形態学的特徴を明らかにすることが重要であるが，そのためには分子解析や免疫組織化学的，臨床病理学的特徴を含めた多方面からの検討が必要である．

　In recent years, the "serrated pathway" concept, wherein serrated lesions of the colorectum are considered as precursor lesions, has been proposed as a new carcinogenic pathway for colorectal cancer and is garnering international attention. However, because serrated lesions of the colorectum are histopathologically and molecularly diverse, sufficient pathological diagnostic criteria have not yet been established. In 2019, WHO（the World Health Organization）classification for gastrointestinal tumors was revised for the first time in nine years, which included the addition of classification and pathological diagnostic criteria for serrated lesions of the colorectum. To establish the criteria for pathological diagnosis of serrated lesions of the colorectum, it is important to understand the lesion's nature and to clarify the histomorphological features that represent the lesion's nature. Hence, there is a need for performing multifaceted evaluations, including molecular analyses, immunohistochemistry, and investigation of clinicopathological features.