Pulmonary intravascular mononuclear cell accumulation in cases of mechanical asphyxia due to external neck compression

Pulmonary intravascular mononuclear cell accumulations have been described in mechanical asphyxia, but their diagnostic value and independence from demographic or post-mortem factors remain uncertain. This study assessed the frequency of these accumulations in asphyxial deaths due to external neck compression compared with non-asphyxial deaths, and evaluated whether the association persists after adjustment for potential confounders. Lung tissue samples from 31 external neck-compression deaths and 151 non-asphyxial controls were examined histologically. A subset underwent immunohistochemical phenotyping. Univariable comparisons were performed using χ2 and Mann–Whitney U tests. A multivariable logistic regression model—including age, sex, post-mortem interval (PMI), and body mass index (BMI)—was used to evaluate the independence of the association. Intravascular mononuclear accumulations were observed in 41.9 % of neck-compression deaths versus 17.2 % of controls (p < 0.01; unadjusted OR 3.47, 95 % CI 1.52–7.96). In the multivariable model, external neck compression remained independently associated with the presence of intravascular accumulations (adjusted OR 2.93, 95 % CI 1.14–7.52; p = 0.025), while age, sex, PMI, and BMI showed no significant effect. Immunohistochemistry confirmed that accumulations consisted of mature mononuclear cell subsets. Pulmonary intravascular mononuclear accumulations occur significantly more often in asphyxial deaths involving external neck compression, and this association persists after adjustment for key demographic and post-mortem variables. Although not specific to mechanical asphyxia, these accumulations represent a practical ancillary marker that may support the diagnosis of neck-compression vitality, especially in cases with limited external findings.