A case of the ‘dapsone syndrome’

Summary The ‘dapsone syndrome’ developed in a 44‐year‐old woman who was treated for pyoderma gangrenosum with 100 mg/day dapsone for about 5 weeks. Symptoms included fever, malaise, jaundice with hepatic dysfunction, lymphadenopathy, mononucleosis and dermatitis. These symptoms disappeared with 30 mg/day of oral prednisolone. A lymphocyte stimulation test with dapsone was positive, as was the delayed‐type intradermal skin test with 0.5 and 0.05% dapsone in saline. Immunohistochemical studies of the rash and skin test reaction revealed that the dominant infiltrating T cells in the upper dermis were of the Leu 2a+ cytotoxic/suppressor‐type rather than the Leu 3a+ helper/delayed hyper‐sensitivity‐type.