Using the inflammatory cell infiltrate to estimate the age of human burn wounds: A review and immunohistochemical study

The burn wound healing process, which is reviewed in this paper, has features that differ from the healing of incised cutaneous wounds. This study used immunohistochemical staining and cell counting to examine the inflammatory cell response in biopsy samples of burn wounds from live human subjects obtained at six hours until 23 days after injury in order to determine how the age of a burn could be estimated. Acute inflammatory cells predominated in samples taken six hours to two days after injury. However, neutrophils were often minimal in early samples or could be present late. Elevated numbers of macrophages tended to be encountered from days 2 to 20, but it was not uncommon to observe a minimal or absent macrophage response. Unexpectedly, there was no trend in the number of lymphocytes. A small study was also made of burn wound samples that had been obtained at post-mortem examination of subjects that died in a fire or up to 77 days after injury from fire. This revealed a similar trend of neutrophil and macrophage accumulation. Additionally, it appeared that an increase in the number of lymphocytes occurred late, from 35 days. In conclusion: If neutrophils predominate, the wound is probably less than a couple of days old. When macrophages are abundant the wound is probably a few days to weeks old. However, as expected from the review of the literature, the inflammatory cell infiltrate may be low or absent in burn wounds, which can render determination of the age of burn wounds difficult.