Childhood Interstitial Lung Disease (ChILD)

Childhood interstitial lung disease (ChILD) refers to a heterogenous group of rare, diffuse lung diseases characterized by impaired gas exchange. Common presenting features include tachypnea (in 75%-93% of patients), hypoxemia, rales, and cough. Persistent hypoxemia and fine rales raise the index of suspicion for interstitial lung disease (ILD). Failure to thrive is also common, due to increased metabolic demand from work of breathing.

Given the common overlapping symptoms of ILDs, classification relies on histologic diagnosis, although genetic testing has emerged as a significant adjunct. The underlying etiologies of these conditions are variable (including developmental, genetic, environmental, and systemic causes) as reflected in the classification system proposed by the American Thoracic Society Committee on ChILD:

(Source: An Official American Thoracic Society Clinical Practice Guideline: Classification, Evaluation, and Management of Childhood Interstitial Lung Disease in Infancy. Am J Respir Crit Care Med 2013; 188:376-394. Reprinted with permission of the American Thoracic Society. Copyright © 2018 American Thoracic Society Table 2. Kurland G et al. American Thoracic Society Committee on Childhood Interstitial Lung Disease (ChILD) and the ChILD Research Network. The American Journal of Respiratory and Critical Care Medicine is an official journal of the American Thoracic Society.)

In infants, another approach to classifying ChILD diseases is to localize the abnormality to one of three areas: the airways, interstitium, or alveoli.

(Adapted from Schematic of the Pathology of Interstitial Lung Diseases by T.B. Kinane, with permission.)

Initial evaluation of children with suspected ILD includes a comprehensive history with attention to family history of ILD or severe neonatal respiratory failure. Infection and sepsis, immunodeficiency, cystic fibrosis, recurrent aspiration, autoimmune disease, congenital heart disease, and pulmonary arterial hypertension should all be excluded. Further evaluation varies and is guided by clinical course and severity of disease.

Diagnostic Tests

• chest radiograph: frequently abnormal but lacks specificity; most often demonstrates hyperinflation

• high-resolution CT scan: findings include mosaic attenuation, hyperinflation, air trapping, ground-glass opacities, nodules, cysts, consolidation, inter- or intralobular septal thickening, and a crazy-paving pattern defined by ground-glass opacities with superimposed interlobular septal thickening and intralobular lines

• pulmonary-function test: demonstrates a restrictive pattern as suggested by decreased FEV₁ and FVC, with a normal-to-elevated FEV₁/FVC

• echocardiogram: to evaluate for congenital heart disease and vascular anomalies masquerading as ILD; pulmonary hypertension can be associated with a worse prognosis

• swallow study: to rule out recurrent aspiration

• laboratory tests: for evaluation of the immune system

• lung biopsy

• genetic testing: may guide prognosis and family planning

Management

Due to the rarity of ChILD, management is frequently guided by expert opinion and experience. Management includes supportive care, supplemental oxygen, antibiotics for acute respiratory infections, minimization of aspiration, and nutritional support.

Use of immunologic therapies such as hydroxychloroquine, azathioprine, and rituximab has been reported in the literature with benefit in individual cases as steroid-sparing agents or in patients who have failed steroid therapy. Precise mechanisms of action have yet to be determined.

Patients with severe lung disease may be referred for lung transplantation.