From Minor Knee Laceration to Multisystem Catastrophe: A Five-Year-Old Boy's Battle With Protein C Deficiency and Purpura Fulminans.

Purpura fulminans (PF) is a rapidly progressive thrombotic emergency. Trauma-induced acquired protein C deficiency is exceptionally rare in pediatric patients. This case adds to the limited literature describing PF triggered by minor traumatic injury, complicated by delayed recognition and resource limitations. A previously healthy five-year-old boy developed rapidly expanding purpura and skin necrosis after a knee laceration from flying debris in Gaza. Lesions progressed to involve the feet, groin, thighs, back, and upper arm, ultimately resulting in 14.5% total body surface area (TBSA) necrosis and right above-knee amputation. Initial workup showed low protein C and extensive microvascular thrombosis, consistent with trauma-associated PF. Management included unfractionated heparin infusion guided by anti-Xa levels, broad-spectrum antibiotics, serial debridements, and staged grafting. Protein C normalized after recovery, and genetic testing was negative. He completed one year of anticoagulation with no recurrence of thrombosis. Early recognition, precise treatment, and multidisciplinary care are lifesaving in trauma-induced PF. Differentiating acquired from congenital protein C deficiency prevents unnecessary lifelong therapy.