Pyogenic granuloma mimicking a colon cancer.

A 59-year-old man with a history of chronic myelogenous leukemia underwent colonoscopy because of altered bowel habit. Conventional colonoscopy showed a reddish, irregular shaped, semipedunculated polyp in the rectum, approximately 10mm in diameter (●" Fig.1). Magnifying endoscopy with indigo carmine revealed a smooth surface without mucosal pits (●" Fig.2). Magnifying endoscopy with narrow band imaging showed many microvessels with a congested network pattern (●" Fig.3). A colon cancer was considered by colonoscopic findings. However, histopathology of biopsies showed inflammatory granulation tissue and no evidence of cancer. Endoscopic ultrasound revealed that the lesion was confined to the mucosal layer and that the submucosal layerwas intact (●" Fig.4). The lesion was removed by endoscopic mucosal resection for accurate diagnosis. Histopathologically, the lesion consistedmainly of inflammatory granulation tissue and was covered with regenerating epithelium. It was diagnosed as a pyogenic granuloma (●" Fig.5 and●" Fig.6). Pyogenic granuloma is a benign lesion of unknown etiology [1]. It is common on the skin and oral mucosal surfaces, but extremely rare in the gastrointestinal tract, especially in the colon [2]. Clinically, it can mimic a colon cancer because of the irregular shape [3]. Gastrointestinal pyogenic granuloma is usually covered with thick exudate [4] and its mucosal surface cannot be observed. This case was not covered with thick exudate enabling the surface to be observed in detail by magniFig.1 Colonoscopy showed a reddish, irregular shaped, semipedunculated polyp in the rectum, approximately 10mm in diameter. Fig.2 Magnifying endoscopy with indigo carmine revealed a smooth surface without mucosal pits. Fig.3 Using narrow band imaging, many microvessels with a congested network pattern were seen.