Case Report: Secukinumab induced pustular eruption in a patient with ankylosing spondylitis.

We report a case of a 33-year-old male with ankylosing spondylitis (AS) who had been receiving secukinumab (150 mg monthly) for 2 years. Approximately 1 year after initiating treatment, the patient developed recurrent, multiple sterile pustules on the palms and soles. Various topical treatments, including corticosteroids and calcipotriol, yielded minimal improvement. 1 week prior to presentation, new pustular lesions emerged on the trunk and extremities, accompanied by pruritus followed by burning sensations and tenderness. Histopathological examination revealed subcorneal pustule formation within the epidermis and sparse lymphocytic infiltration in the dermis. A diagnosis of secukinumab-induced pustular reaction was made. Following the discontinuation of secukinumab and the initiation of upadacitinib (15 mg/day) for over 1 month, the pustules largely resolved, and symptoms were significantly alleviated. This case suggests that IL-17A inhibitors may trigger pustular cutaneous reactions in AS patients. Clinicians should remain vigilant regarding such adverse effects and adjust treatment regimens promptly. JAK inhibitors may provide an effective therapeutic option for managing these drug-induced reactions.