We read with interest the letter by Davies et al (Gut 2007;56:155–6) extending their observations regarding the potential carcinogenicity of methylene blue from the oesophagus to the colon. The use of methylene blue for pan-colonic chromoendoscopy has been proposed to increase dysplasia detection in ulcerative colitis, and it is also used for polyp characterisation in vivo, producing clearer pit patterns than indigo carmine, potentially providing “endohistology”.¹ A safe, rapid, simple method for in vivo endoscopic polyp characterisation could allow substantial reductions in the histopathological workload if formal histopathology were abandoned for small polyps (<10 mm), as 90% of polyps resected are <10 mm and rarely contain cancer. Although no cases of carcinoma were reported in diminutive polyps (<5 mm) in a large series, adenomas 5–10 mm contained carcinoma in approximately 1% of cases.² Carcinoma can be differentiated by the presence of Kudo type V pit pattern. …