Non-infectious Subcutaneous Emphysema of the Upper Extremity: A Unique Mimicker of Necrotizing Fasciitis - A Case Report.

Introduction: Subcutaneous emphysema (SE) of the upper extremity following minor trauma is a rare clinical presentation that can closely mimic necrotizing fasciitis (NF), a life-threatening surgical emergency. This report presents a case of non-infectious SE of the hand, with emphasis on diagnostic strategies to differentiate it from NF and guide appropriate management to avoid unnecessary surgery. Case Report: A 64-year-old male presented to the Emergency Department with swelling and crepitus of the right hand 10 hours after sustaining a minor laceration from a pen knife. The patient reported using hydrogen peroxide for wound irrigation before symptom onset. Clinical examination revealed extensive subcutaneous air on palpation with preserved distal neurovascular status. Laboratory evaluation showed normal inflammatory markers, and the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was 0, indicating low risk for NF. Radiographs and computed tomography imaging demonstrated widespread SE without abscess or cortical destruction. The patient was admitted for close monitoring and empiric antibiotics. Serial examinations remained stable with no signs of clinical deterioration. The patient was discharged on oral antibiotics and remained complication-free with full functional recovery at 1-year follow-up. Conclusion: Non-infectious SE of the upper extremity is an uncommon but important differential diagnosis in cases of post-traumatic soft tissue swelling with crepitus. Careful clinical assessment, use of risk stratification tools, such as the LRINEC score, and appropriate imaging are critical to distinguish benign SE from NF. Awareness of this entity can help prevent unnecessary surgical intervention and improve patient outcomes.