A 49-year-old Caucasian female, with a known irritable bowel syndrome with predominant constipation, presented with a three-month history of progressive diffuse abdominal pain, a bloated belly, and changes in bowel habits including intermittent watery diarrhoea with haematochezia. She had lost 4 kg of weight despite a normal appetite. There was no fever, but she reported night sweats. Laboratory investigation revealed an erythrocyte sedimentation rate of 35 mm (normal value < 20 mm), normal blood count and leucocytes, as well as normal renal and liver function. Investigation of faeces showed infestation with Dientamoeba fragilis and a calprotectin of 336 mg/kg (normal value < 50 mg/kg). Chronic inflammatory bowel disease was suspected. For this reason, a colonoscopy was performed. The entire colon and rectum showed hundreds of small sessile polyps with intact mucosal surface (Kudo classification type 1) (figures 1A and 1B).