Pulmonary hemosiderin in deceased infants: baseline data for further study of infant mortality

Infant lung samples were obtained prospectively at autopsy by medical examiner pathologists in five areas of the United States. Tissues were submitted regardless of the cause of death. Lung sections were stained with Prussian blue to detect deposits of hemosiderin. Fifty-nine cases were evaluated for the study. The four sections examined for each case were taken from the anterior and posterior aspects of the right and left upper lung. Three pathologists independently scanned the lung sections microscopically using a 10x objective lens (with 10x ocular lens) and indicated an "iron score" by indicating for each section if it showed no staining for iron-hemosiderin (Score 0), occasional staining with most fields negative (Score 1), focally abundant staining with most fields having no staining (Score 2), focally abundant staining with most fields showing positive staining (Score 3), or prominent staining throughout the section (Score 4). There was good agreement between pathologists on the iron score for each case. A total iron score was calculated by adding the scores based on each pathologist's observations. The mean total iron score was 6 (range, 1-44), with the range of possible total iron scores being 0 to 48. There was no significant difference between the four lung sections in a given case. Six cases had total iron scores that were at least twice the mean (i.e., total iron score > 12); in five of these cases death was caused by conditions other than sudden infant death syndrome, including one case in which asphyxia was the cause of death. These data are consistent with other reports that pulmonary hemosiderin in deceased infants is suggestive of a cause of death other than sudden infant death syndrome. The data may be useful as baseline data for further studies of infant mortality involving possible pathologic changes in the lungs.