Gall-bladder perforation after long-term dapsone therapy. A 65-year-old man on maintenance dapsone therapy for dermatitis herpetiformis for 30 years was admitted to hospital with acute abdominal pain and vomiting. Investigations revealed a Heinz body haemolytic anaemia. Worsening symptoms prompted an emergency laparotomy that revealed a perforated gall bladder with pigmented biliary calculi. In previous reviews of the haematological abnormalities associated with dapsone therapy, life-threatening cholecystitis has not been described. 