Forensic Image Analyses of Skin and Underlying Muscles as a Tool for Postmortem Interval Delimitation: Histopathologic Examination.

One of the biggest challenges for forensic pathologists is to diagnose the postmortem interval (PMI) delimitation; therefore, the aim of this study was to use a routine histopathologic examination and quantitative analysis to obtain an accurate diagnosis of PMI. The current study was done by using 24 adult male albino rats divided into 8 groups based on the scarification schedule (0, 8, 16, 24, 32, 40, 48, and 72 hours PMI). Skin specimens were collected and subjected to a routine histopathologic processing. Examination of hematoxylin-eosin-stained sections from the skin, its appendages and underlying muscles were carried out. Morphometric analysis of epidermal nuclear chromatin intensities and area percentages, reticular dermis integrated density, and sebaceous gland nuclei areas and chromatin condensation was done. Progressive histopathologic changes could be detected in epidermis, dermis, hypodermis, underlying muscles including nerve endings, and red blood cells in relation to hours PMI. Significant difference was found in epidermal nuclear chromatin intensities at different-hours PMI (at P < 0.001). The highest intensity was detected 40 hours PMI. Quantitative analysis of measurements of dermal collagen area percentages revealed a high significant difference between 0 hours PMI and 24 to 72 hours PMI (P < 0.001). As the PMI increases, sebaceous gland nuclei and nuclear chromatin condensation showed a dramatic decrease. Significant differences of sebaceous gland nuclei areas between 0 hours and different-hours PMI (P < 0.001) were obtained. A combination between routine histopathologic examination and quantitative and morphometric analysis of the skin could be used to evaluate the time of death in different-hours PMI.