When Cellulitis Is Not Cellulitis: Early Necrotizing Fasciitis in the Emergency Department

Necrotizing fasciitis (NF) is an uncommon but rapidly progressive soft-tissue infection characterized by widespread fascial necrosis, systemic toxicity, and high mortality. Early recognition remains a major clinical challenge because initial manifestations frequently resemble benign conditions such as cellulitis or erysipelas. Diagnostic delays are associated with significantly increased morbidity and mortality, particularly when surgical intervention is postponed. We report a case of early necrotizing fasciitis initially diagnosed as uncomplicated cellulitis in the emergency department (ED), illustrating the diagnostic pitfalls encountered in early disease. A middle-aged man presented with acute lower-limb erythema, swelling, and severe pain disproportionate to physical findings. Initial evaluation suggested cellulitis, and empirical antibiotic therapy was initiated. However, rapid clinical deterioration with escalating pain and systemic toxicity prompted further investigation. Cross-sectional imaging demonstrated fascial thickening and soft-tissue gas, raising suspicion for necrotizing fasciitis. Emergent surgical exploration confirmed extensive fascial necrosis requiring aggressive debridement and intensive care support. The patient subsequently underwent multiple surgical procedures and recovered after prolonged hospitalization. This case highlights the importance of maintaining a high index of suspicion for necrotizing fasciitis in patients presenting with presumed cellulitis, particularly in the presence of disproportionate pain, rapid progression, or systemic manifestations. It also underscores the limitations of laboratory-based scoring systems such as the LRINEC score and emphasizes the critical role of early surgical consultation. Timely recognition and prompt surgical intervention remain the most important determinants of survival.