Interstitial haemosiderin in the lungs of sudden infant death syndrome: a histological hallmark of 'near-miss' episodes?

The occurrence of multiple intrathoracic petechial haemorrhages in sudden infant death syndrome is well-documented and undisputed. We describe a study of 24 consecutive sudden infant deaths in which Perls' method for staining of iron in lung sections has been employed in addition to standard post-mortem procedures. Haemosiderin-containing macrophages have been demonstrated in 13 infants in subpleural and interstitial lung tissue in the absence of local fresh interstitial haemorrhage; ten of these infants had no evidence of respiratory tract inflammation and died mainly between one and three months of age. Eleven babies without haemosiderin showed evidence of inflammatory lesions and were predominantly four months or older at death. The demonstration of previous haemorrhagic foci in babies showing no other pathological abnormality may represent a histological hallmark of previous 'near-miss' episodes of hypoxaemia from whatever cause.