Vital reactions in thermal injury: a forensic review of histological, immunohistochemical and molecular markers

Abstract Distinguishing antemortem from postmortem thermal injury remains one of the most challenging tasks in forensic pathology, particularly in cases involving rapid death, extensive charring, or advanced tissue degradation. Classical macroscopic and histological findings provide essential information but often lack sensitivity or specificity when considered in isolation. This review critically examines current evidence on burn vitality markers, with a primary focus on histological and immunohistochemical findings supported by human forensic studies, while contextualizing molecular and microRNA-based (miRNA-based) approaches as largely experimental and translational. Established indicators in forensic casework include erythrodiapedesis, fibrin deposition, inflammatory cell infiltration, and glycophorin-confirmed hemorrhage, together with selected immunohistochemical markers such as HSP70 (Heat Shock Protein 70) and aquaporin-3 (AQP3), which provide supportive evidence of tissue viability. In contrast, molecular biomarkers, such as cytokine gene expression, oxidative stress products, mitochondrial DNA (mtDNA) release, and miRNA signatures, offer mechanistic insight into early cellular responses to thermal injury but currently lack sufficient forensic validation in human autopsy-based studies to support routine medico-legal interpretation. The available evidence indicates that histological and selected immunohistochemical findings constitute the most reliable basis for burn vitality assessment, whereas molecular approaches should be interpreted cautiously as adjunctive and investigational. Diagnostic conclusions therefore rely on the integration of multiple independent findings, evaluated in relation to survival time, tissue preservation, and postmortem artifacts. Overall, this review emphasizes that burn vitality determination requires a cautious, multimodal, and context-driven approach, grounded in validated forensic evidence and supported, where appropriate, by complementary experimental data. Further progress in this field will depend on the systematic validation of emerging markers in human forensic autopsy cohorts.