食道扁平上皮癌の病理診断UPDATE—粘膜下層浸潤距離測定法の標準化とdroplet infiltrationによるリスク層別化の展望

Recent Advances in the Pathological Evaluation of Esophageal Squamous Cell Carcinoma：Standardizing the Submucosal Invasion Depth Measurement and Prognostic Risk Stratification by Incorporating the Droplet Infiltration Evaluation

要旨●食道扁平上皮癌pT1b病変において，内視鏡切除後の粘膜下層浸潤距離の評価は追加治療の判断に重要であるが，その再現性の確保が課題である．本研究では，pT1b病変34例の内視鏡切除材料を対象に，①元の粘膜筋板の高さの仮想線，②腫瘍浸潤により蛇行・断裂した粘膜筋板をつないだ仮想線，③断片化した筋板のうち最も下方に位置する粘膜筋板をつないだ仮想線，から測定する粘膜下層浸潤距離の3測定法について，3名の病理医による評価者間一致率を検討した．その結果，HE染色では方法③，desmin染色では方法②が最も高い一致率を示した．本稿ではさらに，droplet infiltrationなどの組織学的因子を組み込んだリスク層別化の可能性についても述べる．

　In pT1b esophageal squamous cell carcinomas, assessment of submucosal invasion depth after endoscopic resection is essential for determining the need for additional treatment ; however, reproducibility remains a major challenge. This study aimed to evaluate interobserver agreement among three pathologists in the assessment of 34 endoscopically resected pT1b lesions. Submucosal invasion depth was measured using the following three approaches：Method 1, from the original level of the muscularis mucosae ; Method 2, from a reconstructed trajectory of the disorganized muscularis mucosae ; and Method 3, from a line connecting the lowest visible ends of the disrupted muscularis mucosae. In all methods, the measurements were taken perpendicularly to the point of deepest invasion. Among the three methods, Method 3 and Method 2 demonstrated the highest agreement on the hematoxylin and eosin-stained slides and desmin-stained slides, respectively. This paper also discusses the future perspectives on improving prognostic accuracy by incorporating histological factors such as droplet infiltration.