[Changes in the lung connective tissue framework in sudden infant death (SIDS)].

Light microscopy findings are reported on the interstitial connective tissue framework of 45 lungs from babies who died within the first 2 years of life. Thirty were confirmed cases of SIDS and 15 were controls of similar age who died of known causes. The stains applied were H & E, PAS, Prussian blue, Elastica van Gieson, Trichrom (Masson-Goldner), Gomori's silver methenamine and Picro-Sirius polarization (modified). Particular attention was paid to type I and type III collagen, reticulin fibers and ground substance. All investigated cases showed evidence of chronic recurrent interstitial edema in a highly significant frequency and intensity in contrast to the controls. Areas of recent and persistent lymphedema were observed, some of them with reactive fibroplastic activity, which tended towards gradual fibrosis. These changes were irregularly distributed and frequently involved the mural interstitium. Considering the effects of such changes on expansibility, ventilation and perfusion of the lungs, as well as the impairment of gas diffusion, the findings described could be significant in the forensic evaluation of the signs of asphyxia found in most cases of SIDS.