Alveolar Macrophage Counts in Mechanical Asphyxia: A Retrospective Histopathological Study of Autopsy Lungs

Introduction: Alveolar macrophages are key regulators of alveolar homeostasis and are highly sensitive to changes in oxygen availability. Experimental studies have demonstrated that hypoxic stress influences macrophage activation and accumulation within the lung. However, data on alveolar macrophage distribution in human autopsy material remain limited and heterogeneous. Materials and methods: A retrospective histopathological study was conducted on autopsy lung tissue retrieved from the archives of the Institute of Legal Medicine of the University of Modena, Italy. Cases of asphyxial death due to neck compression (hanging, ligature strangulation, and manual strangulation) were compared with nonasphyxial control deaths due to isolated traumatic brain injury. Routine hematoxylin and eosin-stained sections were analyzed. Alveolar macrophages were counted in five nonoverlapping high-power fields per case, and the mean macrophage count per field was used for statistical analysis. Results: A total of 145 cases were included, comprising 51 asphyxial deaths and 94 control cases. Asphyxial deaths showed significantly higher alveolar macrophage counts compared with controls (median 5.4 vs 2.0 macrophages per high-power field; p < .001). Exploratory receiver operating characteristic analysis yielded an area under the curve of approximately 0.87, suggesting a moderate to good discriminatory performance. Discussion: Asphyxial deaths due to neck compression are associated with increased alveolar macrophage counts in routine autopsy lung tissue. These findings support a role for alveolar macrophages in the pulmonary response to acute hypoxic stress. Conclusion: Alveolar macrophage quantification may represent a supportive histopathological feature of asphyxia, although it should be interpreted within a broader multiparametric framework.