ヨード染色による範囲診断が困難であったESD瘢痕上に発生した異時性食道扁平上皮癌の1例

Metachronous Superficial Esophageal Squamous Cell Carcinoma Located Close to a Post-ESD Scar for Which Margin Delineation was Difficult with Lugol Chromoendoscopy, Report of a Case

要旨●食道扁平上皮癌は，異時性多発癌の頻度が高いため，内視鏡治療後の瘢痕上や近傍に異時性病変が再発する症例を経験する．食道扁平上皮癌の側方範囲診断においては，ヨード染色が標準的な診断方法であるが，ヨード不染を示す病態は癌に限らず，異形成，炎症性変化，過角化，錯角化などが挙げられる．また，化学放射線療法後の変化や内視鏡治療後瘢痕の領域で，ヨード淡染〜不染を呈する症例も経験することがある．筆者らは，ESD瘢痕上に発生した異時性食道扁平上皮癌で，ヨード染色により広範にヨード淡染〜不染を呈し，範囲診断が困難であった1例を経験した．本症例ではNBI併用拡大観察が病変の血管構造変化や明瞭なbackground colorationを捉えることができ，範囲診断やマーキングに有用であった．ヨード染色による範囲診断が困難な症例に対するNBIの有用性は，今後さらなる検討が必要である．

　Metachronous ESCC（esophageal squamous cell carcinoma）may occasionally develop near a post-ESD（endoscopic submucosal dissection）scar. Although Lugol chromoendoscopy is commonly used for delineating ESCC, cancerous lesions and other abnormalities such as dysplastic lesions, inflammation, and epidermization may remain unstained by Lugol's solution. Moreover, Lugol-unstained areas in the esophageal mucosa are sometimes observed after chemoradiation therapy or endoscopic resection. Here, we present a case of a metachronous superficial ESCC located close to a post-ESD scar that appeared as an extensive Lugol-unstained area, making it difficult to delineate its margin. In our case, NBI（narrow band imaging）with magnification helped delineate the lesion as it revealed a clearly defined, brownish area with background coloration. However, further studies are required to clarify the usefulness of NBI in cases that are difficult to delineate with Lugol chromoendoscopy.