An inverted hyperplastic polyp with a characteristic colonoscopic appearance

Abstract

A 65-year-old man was referred to our department for polypectomy. A polyp, 20 mm in diameter, was found in the ascending colon on colonoscopy (Figure [1 ] a). The polyp surface was covered by characteristic multiple dimples, long thin vessels, and mucus. Chromoendoscopy with 0.4 % indigo carmine enhanced the appearance of the polyp surface dimples, and subsequent magnification revealed a type II pit pattern according to Kudo’s criteria, leading us to a diagnosis of a large hyperplastic polyp (Figure [1 ] b). Most hyperplastic polyps do not show multiple dimples over their entire surface, and so an unusual histological diagnosis, such as inversion, was suspected before removal of the polyp. Endoscopic mucosal resection using an inject and cut technique was performed, and the polyp was resected en bloc. Histologically, it was indeed found to be an inverted hyperplastic polyp (Figure [2]).