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Childhood interstitial lung disease (ChILD) comprises a heterogeneous
group of chronic pulmonary disorders, characterized by diffuse parenchymal
infiltrates and impaired gas exchange, often leading to hypoxemia. Delineation
of a ChILD classification scheme is complicated, because many disorders
that could be included in the schema also involve the airways and
air spaces, more than the interstitium. The term ChILD syndrome may
be more appropriate, since patients with these disorders share common
symptoms, physical findings, and radiologic abnormalities (see Table 515-1).1,2 In the
past few years, specific entities presenting in this manner that
are unique to children, including inborn errors of surfactant metabolism,
have been recognized.1 This chapter provides an
overview of ChILD with a focus on these recent developments.2 Although
no classification scheme is ideal, a list of ChILD disorders is
given in Table 515-1. It is not possible
to discuss each entity in detail, but some of these disorders deserve
emphasis.
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Disorders of known etiology include aspiration syndromes (see Chapter 511), infectious etiologies, bronchopulmonary
dysplasia (see Chapters 59 and 513),
and certain metabolic disorders (Section 11).
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Hypersensitivity Pneumonitis
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Also known as extrinsic allergic alveolitis, hypersensitivity
pneumonitis (HP) includes a variety of disorders resulting from
an immune response to inhaled organic antigens (Farmer’s
lung, bird fancier’s disease). HP is uncommon but under-recognized
in children. The specific nature of the immune response is uncertain
but is of type III or IV. In contrast to adults, whose exposure
is often in the workplace, the most common cause in children is
exposure to avian antigens.3 The entity
should be suspected if onset of recurrent pneumonias can be linked
to environmental exposures, especially to birds, or changes in the
environment. HP ...