Histological and enzyme histochemical parameters for the age estimation of human skin wounds

Routine histological staining techniques form the basis of a forensic age estimation of human skin wounds and the determination of vitality is aided by the detection of neutrophilic granulocytes which appear earliest about 20-30 min after wounding. A clear granulocyte infiltration and a significant increase in the number of macrophages indicates a post infliction interval of at least several hours. Macrophages containing incorporated particles such as lipophages, erythrophages or siderophages appear earliest at a wound age of 2-3 days similarly to extracellular deposits of hemosiderin, whereas the rarely detectable iron-free pigment hematoidin and spot-like lymphocytic infiltrates in the granulation tissue appear approximately one week or more after wounding. A complete reepithelialization of surgically treated and primarily healing human skin lesions can be expected earliest 5 days after wound infliction and the absence of a complete new epidermal layer indicates a survival time of less than 21 days. Enzyme histochemical methods allow a wound age differentiation especially in the range of a few hours. An increase in nonspecific esterases can be observed earliest approximately 1 hour after wounding followed by other enzymes such as acid phosphatase (approximately 2 h), ATPase (approximately 4 h), aminopeptidase (approximately 4 h) or alkaline phosphatase (approximately 4 h). Positive results, however, cannot be regularly found. Therefore, the detection of reactive changes is useful for a wound age estimation whereas negative findings, which in general must be interpreted with caution, can provide information only in a limited number of histological parameters.