胃癌診断における内視鏡下生検の現状

Endoscopic and Histological Issues in Diagnosing Gastric Carcinoma

要旨　内視鏡診断および生検診断の現状を明らかにし，内視鏡による胃癌の診断過程における問題点を検討した．生検が施行された症例は内視鏡検査総数の32.8％であった．内視鏡診断の感度は84.66％，特異度は99.10％，陽性反応的中度は65.33％となり，内視鏡診断の偽陰性率は15.34％であった．GroupⅠ～Ⅲを胃癌に対する生検診断の陰性，GroupⅣ，Ⅴを陽性とすると，生検診断の感度は96.16％，特異度は99.98％，陽性反応的中度は99.72％となり，生検診断の偽陰性率は3.84％であった．内視鏡診断と生検診断が不一致となる大きな原因は，内視鏡診断の精度が低いためと考えられた．内視鏡診断偽陰性の原因として，内視鏡診断能の不足が58.9％を占めた．診断困難例においては，活動期潰瘍の合併，微小胃癌を含む小さな胃癌などが重要であった．内視鏡診断偽陽性の原因としては，活動期および再発性潰瘍が重要であった．生検偽陰性の原因は，病理診断に起因するもの，病変の特性に起因するもの，内視鏡診断に起因するものの3つに分けられ，それぞれ非常に分化度の高い胃癌，スキルス，そして微小癌を含めた小さな胃癌が重要であった．

　We examined the endoscopic and histological diagnosis of gastric lesions. Biopsies were carried out in 32.8％ of all the endoscopic examinations made of the upper gastrointestinal tract. It was shown that the endoscopic diagnoses were sensitive in 84.66％ of the cases and specifically correct in 99.10％ of the cases. False 15.34％ of the cases were falsely diagnosed as negative. The causes of the false negative endoscopic diagnoses were the impossibility of or the great difficulty of endoscopic diagnosis of the lesion. Twenty patients were falsely diagnosed as positive. Seven of these were cases of the acute stage or recurrence of ulcerative lesions. Sensitivity and specificity of the histological diagnosis by biopsy specimens were 96.16％ and 99.98％ respectively. 3.84％ of the patients with carcinoma were falsely diagnosed as negative by histological diagnosis. The causes of the false negative histological diagnoses by biopsy specimens were difficulty in histological diagnosis and character of the carcinoma and impossibility of endoscopic diagnosis.

　In order to decrease false negative diagnoses by biopsy specimens, it is important to diagnose the lesion correctly endoscopically and perform the biopsy exactly.