Probable paradoxical pyoderma gangrenosum associated with secukinumab in a patient with severe plaque psoriasis

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis increasingly associated with biologic therapies. We report a probable case of paradoxical PG associated with secukinumab in a 40-year-old woman with severe plaque psoriasis (PASI 60; DLQI 25). Fifteen days after treatment initiation, painful inflammatory lesions developed on the gluteal region and posterior thighs, followed by rapidly progressive scalp ulcerations. Histopathologic examination of the active ulcer edge demonstrated epidermal ulceration with fibrinoneutrophilic crust formation and a predominantly lymphocytic inflammatory infiltrate. Repeated bacterial, fungal, and mycobacterial cultures were negative. Although histopathologic findings were not classic for PG, clinicopathologic correlation, fulfillment of multiple Delphi minor criteria, a PARACELSUS score of 20, and temporal association with secukinumab supported the diagnosis. Secukinumab was discontinued, systemic corticosteroids produced rapid and marked pain improvement within 48 hours, and subsequent cyclosporine therapy resulted in progressive clinical improvement. This case highlights the diagnostic complexity of PG and the importance of recognizing paradoxical neutrophilic reactions associated with IL-17 inhibition.