Colon Cancer under Type IV Pit Pattern Adenoma with Multiple Metastases in Lymph Nodes and Bones: A Case Report

With the development of magnifying colonoscopy and an understanding of pit patterns of tumors, the diagnostic accuracy of tumors in the colon has improved. However, we encountered an aggressive, 2.5-cm diameter tumor in the colon, most of which grew under the component of tubular adenoma with high-grade atypia. This case represents an atypical example of colon cancer and we consider it worth reporting.