A case of advanced colon cancer measuring 8 mm in diameter

Abstract

A 68 year-old male who had underwent sigmoidectomy for colon cancer on April 6, 1992 was admitted to our hospital. Colonoscopy revealed a small flat-elevated lesion with converging folds of the ascending colon. On preoperative evaluation of a massive invasion to the submucosal layer, right hemicolectomy was performed on September 8, 1994. Macroscopic examination of the resected specimen showed a slightly elevated tumor with converging folds, measuring 5 x 8 mm in diameter. Histopathology revealed a well differentiated adenocarcinoma invading to the subserosal layer. No residual adenomatous tissue was identified, and no metastasis was found in 14 lymph nodes. The proliferating activity of thin small advanced colon cancer was determined by double staining technique of Ki-67 and argyrophilic nucleolar organizer resions (AgNOR) using formalin-fixed paraffin-embedded sections. Labeling index of Ki-67 monoclonal antibody (MIB 1) was 7.3 %. Although the Ki-67 negative cells had low AgNOR counts (mean 2.50), the Ki-67 positive cells had high AgNOR counts (mean 9.98 per nucleus).