Adult-onset Still's disease with prurigo pigmentosa-like skin eruption.

A 34-year-old woman with adult-onset Still's disease (AOSD) developed prurigo pigmentosa-like lesions on her chest and upper back in addition to the typical rash of AOSD. A biopsy specimen taken from the upper back showed characteristic features of prurigo pigmentosa. The eruption and fever subsided immediately after the administration of 40 mg/day prednisolone, but arthralgia persisted even after intravenous pulse methylprednisolone therapy in combination with immunosuppressive drugs. Various atypical skin rashes, including prurigo pigmentosa-like lesions, have been reported in association with AOSD. Therefore, one should carefully follow the clinical course of a patient in order not to overlook these atypical cutaneous manifestations of AOSD.