Early Invasive Colon Cancer that Transformed from a Sessile (Is Type) Polyp into a Concave Lesion (IIc+IIa Type), Report of a Case Yoshiharu Uno 1 , Akihiro Munakata 1 1The First Department of Internal Medicine, Hirosaki University School of Medicine Keyword: 早期大腸癌 , 形態変化 pp.1671-1674
Published Date 1998/11/25
DOI https://doi.org/10.11477/mf.1403103876
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 A sessile polyp 8 mm in diameter was observed by colonoscopy in the sigmoid colon of an 81-year-old man. The lesion was classified Is type, and no biopsy was undertaken. However, 11 months later, the polyp transformed into a concave lesion (IIc + IIa type), and this was removed by saline-assisted polypectomy. The resected lesion was 10 mm in diameter. Stereomicroscopic examination revealed an irregular surface without an adenomatous pit pattern in the concave area. Histologically, well differentiated adenocarcinoma with marked fibrosis was revealed in the concave area, but no adenoma component was evident, even in the surrounding ridge. The carcinoma had massively invaded the submucosal layer. The initial colonoscopic finding was typical polypoid lesion (Is type). However, the findings at the second colonoscopic examination showed a typical superficial depressed-type lesion (NPG-IIc+IIa type). This is the first report of an early invasive colorectal cancer that changed from a sessile type to a concave type without biopsy. We think that this case is interesting for considering the natural course of colorectal cancer.

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