Assessment of pulmonary and intrathymic hemosiderin deposition in sudden infant death syndrome

The aim of this study was to stain lung and thymus gland sections that had been taken from infants who had died of sudden infant death syndrome (SIDS) for interstitial hemosiderin and to compare the results with those obtained for controls. There were two groups of SIDS infants, one with, and a second group without, histories of apparent life-threatening events (ALTEs). No significant difference in numbers of cases with interstitial hemosiderin deposition was found between SIDS infants with histories of ALTEs (n = 4 of 12, 33.3%), SIDS infants without histories of ALTEs (n = 4 of 22, 18.2%), and controls (n = 4 of 24, 16.7%). However, if four of the control cases with histories of previous chest trauma were excluded, there was a significantly greater number of cases with pulmonary interstitial hemosiderin in the SIDS infants with histories of ALTEs compared with the subgroup of control infants with no previous chest trauma (n = 1 of 20, 5%) (P < .05). No relationship could be established between the timing of the ALTEs, the type of resuscitation or age of the infant at death, and the presence of hemosiderin. None of the sections of thymus gland stained positively for hemosiderin. Positive staining for pulmonary interstitial hemosiderin, therefore differentiated a group of SIDS infants with histories of previous ALTEs from a subgroup of control infants with no histories of previous chest trauma. However, pulmonary interstitial hemosiderin staining could not be used with certainty to confirm or exclude previous ALTEs in individual SIDS cases as not every SIDS case with a history of an ALTE stained for pulmonary interstitial hemosiderin. In addition, positive staining occurred for SIDS infants without histories of ALTEs and also for control infants who died of other causes.