An unusually pigmented colon: LANCET case report
A 28-year-old woman presented with a chronic history of constipation, abdominal pain, and bloating. There was no history of weight loss or haematochezia. She had anorexia nervosa for which she was engaged with psychiatric care. She was a non-smoker and consumed minimal alcohol.

She used glycerine suppositories as required. Initial treatment with polyethylene glycol improved the symptoms. Blood tests revealed a normocytic anaemia of 103 g/L and normal haematinics; faecal calprotectin was negative.

A colonoscopy was done that showed significant discolouration of the bowel mucosa from caecum to distal descending colon. The terminal ileum and rectum were of normal colour.

Biopsy samples confirmed normal gland architecture with abundant pigment laden macrophages in keeping with melanosis coli.