The sulfone syndrome secondary to dapsone prophylaxis in a patient undergoing unrelated hematopoietic stem cell transplantation

Dapsone is commonly used for pneumocystis carinii pneumonia (PCP) prophylaxis in immunocompromised patients. It has been used as an alternative therapy in the hematopoietic stem cell transplant (HSCT) setting in patients who can't tolerate trimethoprim-sulfamethoxazole. The Sulfone syndrome is not a well-known sequela of dapsone therapy and occurs at various doses, ranging from 50-300 mg/d. In all cases the syndrome occurs within 2 months of initiating therapy. Its clinical manifestations include: fever, methemoglobinemia, hemolytic anemia, exfoliative dermatitis and transaminits. A 51-year old female underwent a matched unrelated hematopoiectic stem cell transplant for acute mylogenous leukemia. Dapsone therapy was initiated on day +28 at a dose of 100 mg/day for PCP prophylaxis secondary to the patient's history of a sulfonamide allergy. On day +59, one month after initiation of therapy she developed hepatitis, hemolytic anemia, fever and methemoglobinemia of 8%. She was transferred to the intensive care unit and subsequently developed an exfoliative dermatitis. We conclude that the clinical presentation of this patient after HSCT on dapsone therapy coincide with the sulfone syndrome not previously described in a patients after HSCT.