Purpura Fulminans Mimicking NSTI: A Limb-saving case of Haemophilus influenzae Infection

Background Purpura fulminans is a life-threatening thrombotic disorder characterized by disseminated intravascular coagulation and hemorrhagic skin necrosis. Severe cases may be complicated by septic cardiomyopathy requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for circulatory support. The clinical presentation of purpura fulminans closely resembles that of necrotizing soft tissue infections (NSTI), which makes differentiation challenging. Accurate differentiation is crucial for limb preservation strategies. Case Presentation A 52-year-old man with a history of hypertension presented with hypothermia, widespread purpura, and severe bilateral leg pain. Suspecting NSTI, exploratory incisions were performed, revealing asymmetric tissue findings. Despite maximal vasopressor support, he remained hemodynamically unstable and required VA-ECMO. During ECMO management, the patient developed compartment syndrome requiring fasciotomy. Blood and wound cultures grew Haemophilus influenzae . With multidisciplinary management, including prone positioning and fluid removal with continuous renal replacement therapy (CRRT), ECMO was successfully weaned on day 3. Although persistent infection and rhabdomyolysis-induced acute kidney injury (AKI) necessitated amputation of the left leg, the right leg was salvaged with skin grafting. The patient was eventually weaned from dialysis and discharged ambulatory with a prosthetic limb after rehabilitation. Conclusions This case highlights the diagnostic challenge of distinguishing purpura fulminans from NSTI and emphasizes the importance of early ECMO weaning to improve patient outcomes. A multidisciplinary strategy integrating circulatory stabilization, fasciotomy, and careful limb preservation may optimize survival and functional recovery in patients with severe purpura fulminans. Differentiating between purpura fulminans and NSTI is crucial for preventing unnecessary amputations and preserving limb function.