Fatal spider envenomation: a systematic review of autopsy findings

Background: Fatal spider envenomation is exceptionally rare in contemporary medical practice; however, sporadic reports continue to appear in the forensic literature, often characterized by diagnostic uncertainty and heterogeneous documentation. This systematic review critically evaluated all published fatal cases attributed to spider envenomation, with emphasis on autopsy findings, histopathological patterns, and medico-legal robustness of causal attribution. Results: A systematic search of PubMed/MEDLINE, Embase, and Scopus was conducted from database inception to 14 February 2026 in accordance with PRISMA 2020 guidelines. Twelve studies met predefined inclusion criteria and were included in the qualitative synthesis. Seven cases (58%) were supported by autopsy findings, while five were clinically well-documented fatalities without post-mortem examination. Loxosceles accounted for most cases (8/12), followed by Latrodectus (3/12) and Atrax (1/12). Three recurrent genus-specific patterns emerged. Loxosceles envenomation showed a hemolytic–coagulopathic profile characterized by intravascular hemolysis, disseminated intravascular coagulation, and acute renal injury. Latrodectus cases demonstrated a predominantly cardiotoxic pattern with myocardial injury and pulmonary edema. Atrax envenomation was associated with a neurotoxic–pulmonary presentation marked by severe pulmonary edema and autonomic instability. Conclusion: Although the number of cases is limited, the recurrence of distinct pathological patterns supports biological plausibility. Nevertheless, substantial risk of misclassification persists, particularly in the absence of entomological confirmation or systematic exclusion of alternative causes of sudden death. Fatal spider envenomation should therefore be interpreted through a structured forensic framework integrating exposure plausibility, clinicopathological coherence, and exclusion of competing causes of death.