A Case of Salazosulfapyridine-Induced Hypersensitivity Syndrome in a Rheumatoid Arthritis Patient with Relapse of Skin Erythema

We experienced a rare case of drug-induced hypersensitivity syndrome (DIHS) in which salazosulfapyridine (SASP) reactivated human herpesvirus 6 (HHV-6) and cytomegalovirus (CMV), which resulted in a relapse of skin symptoms after changing to mizoribine. At the time of recurrence of skin erythema after the initiation of mizoribine, the serum DNA titers of not HHV-6 but CMV were elevated. A drug-induced lymphocyte stimulation test was negative for mizoribine but positive for SASP. In this case, DIHS developed with SASP in association with HHV-6 and CMV reactivation. The immunocompromised state induced by herpes virus reactivation and mizoribine might have caused the relapse of skin erythema.