356 Investigation of the Variable Histopathology of Burn Eschar

Early excision of burn eschar is an established practice among burn surgeons as a necessary intervention to remove the nidus of bacterial growth that leads to infection and sepsis. The purpose of this study was to examine histologic differences of burn eschar in relation to the time of injury and to investigate mediators within the eschar that may have systemic effects. Patients expected to undergo eschar excision and grafting procedures after thermal injury were prospectively enrolled in this study. Samples of burn eschar taken from the first pass with a Weck knife were collected at the time of the first burn excision and stored in formalin. Hematoxylin and eosin (H&E) staining was performed, and images were analyzed using ZEN software from ZEISS Microscopy. Samples from 21 patients were collected and analyzed. Average TBSA was 7% (range: 1-30%). The majority of patients (n=12) underwent excision on post-burn day (PBD) 2. Three patients underwent excision on PBD 0 or 1, and six patients had excision on PBD 3 or 4. On review of H&E, eschar that was excised on PBD 3 or 4 was noted to have increased neutrophil infiltration and frank necrosis when compared to earlier excised samples. Presence of viable tissue below necrotic layers was also dependent on the anatomic location of the injury as eschar from hand and foot injuries often demonstrated full-thickness necrosis. Histologic variability of excised burn eschar is associated with time from injury and anatomical location. While complete excision of burn eschar should be achieved, a balance must be found to leave viable tissue for healing and skin graft success. A better understanding of the histopathology of burn eschar will help clinicians in treating thermal injuries. Further work on these samples will examine the prevalence of mast cells, elastin, and lipid mediators and correlate these findings with long-term complications like hypertrophic scarring, chronic pain, and pruritis. Recognition of these associations can further guide precise timing of burn eschar excision.