Refractory Idiopathic Infantile Pyoderma Gangrenosum Successfully Treated With Infliximab: A Case Report

Pyoderma gangrenosum (PG) is a noninfectious neutrophilic dermatosis that can occur either idiopathically or secondary to various systemic conditions. PG is rare in childhood and even rarer in infancy. Due to its rarity, the pathophysiological mechanisms remain unclear. Although systemic glucocorticoids are considered the first-line therapy, no standardized second-line or subsequent therapeutic approach has been established, particularly for refractory cases. In this report, we present a case of infantile idiopathic PG showing sustained clinical improvement after the addition of the anti-tumor necrosis factor (TNF)-alpha antibody infliximab (IFX). In addition, we conducted multiplex cytokine analysis to explore the patient's inflammatory profile and provide preliminary observations regarding the inflammatory milieu associated with this condition. The patient, a 9-month-old infant, developed multiple pustules and ulcerative skin lesions on the face and extremities following Bacillus Calmette-Guérin (BCG) vaccination. Pathogen investigations were all negative, and the diagnosis of PG was made based on clinical findings, supported by histological features and exclusion of other conditions. After initial treatment with glucocorticoids and cyclosporine, remission was achieved; however, repeated relapses occurred. IFX was subsequently initiated, resulting in significant clinical improvement. Serum cytokine profiling at the onset revealed a broad elevation of proinflammatory cytokines, including soluble TNF receptors 1 and 2, with a pattern partially overlapping with that observed in Kawasaki disease. The clinical course and cytokine analysis results suggest that IFX may be a viable treatment option for refractory PG, even in infants.