Lupus erythematosus with leflunomide: induction or reactivation?

Background: Leflunomide is a new oral disease modifying antirheumatic drug with a good safety profile. Case report: The first case of lupus erythematosus in a 58 year old white woman after administration of leflunomide for primary Sjogren's syndrome is reported. The relationship between induced lupus and leflunomide was confirmed by the resolution of the skin rash when the drug was stopped and its recurrence when it was reintroduced following a dose-response effect. Discussion: Peripheral blood cells from this patient, from 15 patients with rheumatoid arthritis, and from healthy controls were used in a bioassay, which suggested that leflunomide affected the Th1/Th2 balance. Such a side effect might be related, in part, to the anti-tumour necrosis factor a activity of leflunomide.