Idiopathic interstitial pneumonitis in children: a national survey in the United Kingdom and Ireland.

Interstitial lung disease (ILD) of unknown etiology in immunocompetent patients is rare in children. A national survey was carried out in the United Kingdom and Ireland over a 3-year period in order to identify prevalence, age distribution, histopathology, natural history of the illness, and response to current treatment.Forty-six cases were identified, including 29 males and 17 females. Seventy-six percent presented in the first year of life. Nine (16%) occurred within four families. Conventional treatment with pulsed methylprednisolone, prednisolone, or hydroxychloroquine, singly or in combination, resulted in an excellent response in 65% of cases. Seven children died (15%). The recurrence risk for further children within the same family to develop ILD is estimated to be approximately 10%. The prevalence rate of this condition in the United Kingdom and Ireland during the period of study for children aged 0-16 years is estimated to be 3.6 cases/million.