Microscopic inflammatory foci in burn scars: data from a porcine burn model.

Background: Hypertrophic scars in burn victims usually occur after delayed wound healing and the active phase of scar formation can persist substantially even after wound closure. Currently, the pathophysiology of the hypertrophic scar is not completely understood. This study investigated the inflammatory response in scar tissue at week 6 post-burn injury.
Methods: A porcine deep dermal partial thickness burn model was used. At week 6 post-burn, a total of 528 scar biopsies from 72 burn scars (7-8 biopsies from each scar) and 174 normal skin biopsies from 18 pigs were collected and examined histologically.
Results: Microscopic inflammatory foci were identified in 17% (89/528) of scar biopsies. These microscopic inflammatory foci do not contain any irritant materials, are composed largely of polymorphonuclear cells with other inflammatory cells including multinucleate giant cells and show acute on chronic inflammatory response that has not been described previously in burn scars. Importantly, they are present in a significantly lower number in burns surgically debrided than in burns which have not been debrided.
Conclusions: This study identifies microscopic inflammatory foci in the porcine scar tissue layer and recommends thorough cleaning/debriding of burned necrotic tissue in order to minimize the formation of these inflammatory foci in scar tissue.