Interstitial lung disease (ILD) includes a large group of disorders that affect the interstitium part of the lung. The interstitium lies between the alveolar sacs in the lung where gas exchange occurs. The small air tubes (called bronchioles) may also be affected.

In interstitial lung disease, the interstitium can be abnormal due to:

• Scar tissue (called pulmonary fibrosis)
• Buildup of too many or different cells
• Injuries or changes to the lung structure

Interstitial lung disease is uncommon in children.

Signs and Symptoms of ILD

• Fast breathing (called tachypnea)
• Sinking in of the areas below the ribs, between the ribs, and in the neck with breathing (called retractions)
• Abnormally low amount of oxygen in the blood (called low oxygen saturations)
• Crackle sounds in the lungs that are heard with a stethoscope
• Chronic cough
• Shortness of breath, which might include trouble with exercise or physical activity
• Problems growing and gaining weight
• Reflux (food or drink travels from the stomach up the esophagus to the throat or mouth)
• Many episodes of pneumonia
• Chest CT scans that show abnormalities throughout both lungs

Most children with ILD show respiratory symptoms all the time, even when there is not an infection present. Children with ILD may have only some of the symptoms.

Diagnosis of ILD

• Visits with a lung doctor (called a pulmonologist)
• Tests may be done to make sure your child does not have cystic fibrosis, a lung infection, heart problems, or other health problems

Testing for ILD may include one or all of the following:

• Blood tests
• Bronchoscopy
• High resolution chest CT scan
• Pulmonary function tests or infant pulmonary function tests
• Lung biopsy

Decisions about specific testing may depend on:

• The age of the child
• Other medical problems
• How long symptoms have been there
• How bad the symptoms are
• Whether the symptoms are getting better or getting worse
• History of ILD in family members

Causes of ILD

There are many different causes of ILD.

Associated Disorders

• Connective-tissue diseases (also called collagen vascular disease)
• Pulmonary hemorrhage syndromes including capillaritis, Goodpasture’s syndrome or vasculitis
• Langerhans cell histiocytosis
• Sarcoidosis
• Storage disorders
• Lymphoproliferative disorders
• Eosinophilic disorders
• Neurocutaneous syndromes

Types of ILD in Children

Some types of ILD common for infants and young children include:

• Disorders of lung development and lung growth:
• Alveolar capillary dysplasia with misalignment of the pulmonary veins
• Pulmonary hypoplasia
• Bronchopulmonary dysplasia (BPD)
• Pulmonary interstitial glycogenosis (PIG)
• Neuroendocrine cell hyperplasia of infancy (NEHI)
• Disorders of surfactant production or alveolar proteinosis due to SP-B genetic mutations, SP-C genetic mutations, ABCA-3 genetic mutations, NKX2-1 genetic mutations, GMCSF receptor deficiency, or lysinuric protein intolerance, or others
• Certain surfactant disorders can also occur in older children and adults.

Other types of ILD can start at any age.

Some ILD disorders occur along with other medical problems, meaning parts of the body other than the lung are also likely to be affected.

Some ILD disorders may be due to problems with the function of the immune system.

• Autoimmune pulmonary alveolar proteinosis due to auto-antibodies to GM-CSF
• Follicular bronchiolitis / lymphocytic interstitial pneumonitis, constrictive bronchiolitis, or lymphoproliferative disorder are often related to immunodeficiency.

Some ILD disorders may occur due to lung injuries.

• Aspiration
• Hypersensitivity pneumonitis

• Bronchiolitis obliterans

Some disorders are due to problems with blood vessels or lymphatic vessels and can look like ILD.

• Lymphangiomatosis, lymphangiectasia and lymphatic malformations
• Veno-occlusive disease
• Pulmonary arterial vasculopathy

Treatment for ILD

Different treatments are used for different types of ILD. Understanding the cause is important to decide on treatment. Some treatments may include:

• More oxygen (not every child needs it)
• More nutrition to help gain weight and grow
• Flu shot every year to lower the chance of getting infections
• Different medications, depending on the type of ILD