Subacute thyroiditis in a patient with psoriatic arthritis switched from secukinumab to adalimumab: a case report and literature review.

A 71-year-old Japanese female with psoriatic arthritis (PsA) was admitted for fever and neck pain. Her medication had been switched from secukinumab, an interleukin (IL)-17A inhibitor, to adalimumab, a tumour necrosis factor (TNF)-α inhibitor, due to secondary failure for PsA. She was diagnosed with subacute thyroiditis (SAT) on the basis of thyroid hormone levels and thyroid ultrasound findings. Her SAT symptoms improved with prednisolone administration (15 mg/day). Following the administration of ixekizumab, an IL-17A inhibitor, her PsA improved without SAT relapse. SAT mechanism associated with TNF inhibitors remains unknown, but cytokine imbalance may be involved.