Melanosis coli or ischaemic colitis? That is the question.

To cite: Ricciuti B, Leone MC, Metro G. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2015212404 DESCRIPTION In June 2015, an 83-year-old man presented to the emergency department of Santa Maria della Misericordia Hospital in Perugia, Italy, with abdominal pain, bloating, worsening of chronic constipation and rectal bleeding. The physical examination at our department did not reveal abnormal findings, and laboratory investigation turned out negative. Consequently, the patient underwent an immediate colonoscopy, which unveiled the presence of congested and prolapsing internal haemorrhoids and an uneven brown to black staining of the colonic mucosa, apparently associated with scattered ulcers (figure 1). The endoscopic exploration was subsequently interrupted for precautionary reasons, suspecting an ischaemic colitis. However, multiple biopsies were randomly performed. Surprisingly, there was no evidence of bowel ischaemia on histopathological examination, which conversely revealed an increase in the number macrophages filled with brown-coloured pigment granules in the lamina propria and muscularis mucosa, thus confirming the diagnosis of melanosis coli (figure 2). The patient’s medical history was relevant for consumption of anthraquinonecontaining laxatives for 10 years. Melanosis coli is an unusual brownish discolouration of the colonic mucosa, and detected on endoscopy or histopathological examination. This condition often develops within 5 months of anthraquinone-based laxative use (aloe, cascara sagrada, frangula, senna, rhubarb), and is widely recognised to be benign and reversible within 6–12 months of stopping laxatives. Although early studies reported potential mutagenic effects