Fatal paraquat poisoning: a light microscopic study in eight autopsy cases.

Eight autopsy cases of paraquat poisoning from 1980 to 1990 were studied by light microscopy. An attempt was made to correlate the severity of poisoning, as assessed by the blood paraquat concentrations and the time between ingestion and treatment, with the survival periods and pathological changes. Six of the patients were male. The mean age was 21 years (range 12-33 years). The blood paraquat concentrations on admission ranged from 0.04 to 4.27 micrograms/ml. The survival periods were between 26 hours and 59 days. The main causes of death included circulatory collapse in one patient with 26 hours survival, and acute alveolar injury of the lungs and acute tubular necrosis or diffuse cortical necrosis of the kidneys in 4 patients who survived less than 7 days. Pulmonary proliferative changes leading to respiratory failure were detected in the remaining patients, who survived 11, 17, and 59 days. The liver revealed bile duct injury in the portal areas, centrolobular cholestasis, fatty metamorphosis, and inconspicuous centrolobular hepatic necrosis. The adrenal glands showed diffuse cortical necrosis in 3 severe cases. Mild acute pancreatitis was evident in one case. The brain was edematous with or without focal minimal hemorrhages. Toxic myocarditis, myositis, and aplasia of erythropoiesis, as previously described, were not present in this study. The severity of poisoning seems to correlate reversely with the survival periods and directly with degrees of pulmonary damage and adrenal cortical necrosis.