THE VALUE OF CLASSIFYING INTERSTITIAL PNEUMONITIS IN CHILDHOOD ACCORDING TO DEFINED HISTOLOGICAL PATTERNS

Aims: Interstitial pneumonitis in children is very rare and most cases have been classified according to their counterparts in adults, altho ugh the term 'chronic pneumonitis of infancy' has recently been propos ed for a particular pattern of interstitial lung disease in infants, W e reviewed our paediatric cases of interstitial pneumonitis, first, to look at the spectrum of histological patterns found in this age group and, second, to determine whether the classification of such cases in childhood is both appropriate and worthwhile, Methods and results: Tw enty-five of 38 open lung biopsies showed an overlapping spectrum of i nterstitial pneumonitis, including three cases that fulfilled the hist ological criteria for chronic pneumonitis of infancy, There were 11 ca ses of reactive pulmonary lymphoid hyperplasia (either lymphoid inters titial pneumonitis or follicular bronchiolitis), five of which were as sociated with abnormalities of the immune system. Four cases were clas sified as desquamative interstitial pneumonitis and the remaining seve n cases were classified as nonspecific interstitial pneumonitis, There were no cases with the histological features of usual interstitial pn eumonitis, Most patients responded to steroids but tended to have a re sidual deficit in lung function, Mortality appeared to be associated w ith presentation at a young age. Conclusion: Classification of interst itial pneumonitis according to their adult counterparts is appropriate for this younger age group and can provide valuable information for t he clinician, The term 'chronic pneumonitis of infancy' refers to a sp ecific histological pattern, but whether it represents a separate dise ase or a reflection of pulmonary immaturity remains to be proven.