Post-infectious Purpura Fulminans in a Healthy Child: A Case Report

Introduction: Purpura fulminans (PF) is a rare and life-threatening thrombohemorrhagic disorder characterized by rapidly progressive purpuric skin lesions caused by dermal microvascular thrombosis and disseminated intravascular coagulation. Post-infectious PF is an uncommon variant in children and is typically associated with transient acquired deficiencies of natural anticoagulant proteins. Case Presentation: A previously healthy 3-year-old girl presented with rapidly progressive painful violaceous plaques on both shins. She was afebrile and hemodynamically stable. Laboratory studies revealed disseminated intravascular coagulation and severe acquired Protein S deficiency with anti-Protein S antibodies. Diagnosis of PF was made. Microbiological testing was positive for Streptococcus species and metapneumovirus, suggesting a post-infectious trigger. Despite early treatment with antibiotics, anticoagulation, fresh frozen plasma, and intravenous immunoglobulins, the lesions progressed to full-thickness skin necrosis requiring surgical debridement and split-thickness skin grafting. Coagulation parameters and Protein S levels normalized within two weeks. Conclusion: Post-infectious PF should be suspected in children presenting with rapidly progressive purpuric lesions following recent infection. Early recognition and aggressive multidisciplinary management are essential to prevent life-threatening complications and limit permanent tissue damage.