Histopathological findings of the lung and trachea in sudden infant death syndrome: review of 105 cases autopsied at Dade County Medical Examiner Department.

A histopathological study of respiratory tract in sudden infant death syndrome (SIDS) was performed on the case files of Dade County Medical Examiner Department, Miami, Florida, U.S.A. over a span of 40 months from September 1989 through December 1992. Microscopic slides of the lung and trachea were collected from 105 SIDS cases and reviewed. Fifty cases of sudden infant death of recognized causes were also analyzed as a control. The microscopic findings with its severity were recorded on each case. Two major findings, namely pulmonary congestion and edema were noted in 83 and 76% of SIDS cases respectively, and in 72 and 60% of explained deaths. No differences were statistically significant between two groups despite the slight dominance in SIDS cases. Some "typical" findings such as increase of alveolar macrophages, emphysema and atelectasis mainly due to cardiopulmonary resuscitations were commonly found. However, statistical analysis of the incidence of these findings failed to disclose any significant difference. Acute and/or chronic inflammation of the trachea was noted in 21% of SIDS cases, which was consistent with the history of the affected infants stated by the guardians. Minimal to mild bronchitis and pneumonia were found in 8 and 7% of SIDS cases respectively. There were a few cases with some pneumonia which fell into "the gray area" between SIDS and explained deaths. Besides a complete autopsy, scene investigation and review of postnatal medical history of the infant are essential to make a diagnosis of SIDS.