Secukinumab-induced systemic lupus erythematosus in psoriatic arthritis.

A 68-year-old male treated with secukinumab for psoriatic arthritis suspended treatment for three months due to COVID pandemic. Upon secukinumab reintroduction, anorexia and weight loss ensued and four months later he had an abrupt onset of low-grade fever, fatigue, flu-like symptoms, dyspnoea and widespread inflammatory arthralgias. Laboratory investigations showed de novo anaemia, leukopenia, lymphopenia, cytocholestasis, elevated acute phase reactants, C3 complement consumption, proteinuria (1630mg/24h), active urine sediment, positive antinuclear (1:1280) and anti-double-stranded DNA (212.3 IU/mL) antibodies. Chest imaging showed peripheral pulmonary embolism, lobar pneumonia, and a small bilateral pleural effusion. Drug-induced lupus erythematosus (DILE) was suspected, and the patient was hospitalised. Secukinumab was discontinued and treatment with enoxaparin, antibiotics, enalapril, hydroxychloroquine and prednisolone 0.5mg/kg qd was started. Clinical and laboratorial remission ensued after one month except for proteinuria (decreased to 653mg/24h). Proliferative lupus nephritis was assumed and mycophenolate mofetil was introduced, with sustained complete remission over a 33-month follow-up.This is the second reported case of systemic secukinumab-associated DILE, and the first with renal involvement. Clinical and laboratory features of DILE are reviewed and compared with previously described cases.