Interstitial Lung Disease

Jennifer A. Rama and Leland L. Fan

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.

INTERSTITIAL LUNG DISEASES OF KNOWN ETIOLOGY

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).

HYPERSENSITIVITY PNEUMONITIS

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 from hay or mold (especially in aerosolized water) exposure occurs less commonly in children. An acute form results in symptoms of fever, chills, malaise, cough, chest tightness, dyspnea, and/or headache within hours of antigen exposure. Chest radiographs are either normal or show a “ground-glass” appearance with micronodular interstitial pattern. Symptoms resolve within 12 hours to several days upon cessation of exposure. An intermittent or subacute form has also been described in which patients have symptoms of chronic cough, dyspnea, fatigue, and often pleurisy.

Table 515-1. Spectrum of Interstitial Lung Disease in Children

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