INTRODUCTION, DEFINITION, INCIDENCE, AND CLASSIFICATION
Interstitial pneumonitis (IP) in children is now being recognized earlier and with increased frequency as a cause of chronic respiratory symptoms. Confirmation of the diagnosis, histologic classification, and management depend on studies of tissues obtained from lung biopsy. Since physicians are reluctant to utilize invasive procedures such as lung biopsy in children, the exact incidence of this entity is not accurately known. There are no pathognomonic clinical or laboratory features of interstitial pneumonitis other than histologic findings on lung biopsy. Since therapy depends upon accurate diagnosis this procedure is justified when symptoms and findings suggest this diagnosis. The timing of the biopsy must be individualized depending on the severity and progression of the clinical and/or roentgenographic findings. The diagnosis of IP in the immunocompromised host calls for a prompt aggressive approach to differentiate infectious causes from drug-induced pulmonary disease. Recently a rapid and safe technique, thoracoscopy, has been reported to provide accurate histologic and bacteriologic diagnosis in immunosuppressed children (Rodgers et al).
IP is a broad, inclusive term used to describe tissue response which takes place predominately in the supporting structures (interstitium) of the lung rather than within the alveoli. Multiple etiologies may result in similar clinical, histologic, and roentgenographic manifestations.
Hematologic emergencies
