This is a medical question of type : exams and tests 
 How to diagnose Childhood Interstitial Lung Disease ? 
 Doctors diagnose childhood interstitial lung disease (chILD) based on a child's medical and family histories and the results from tests and procedures. To diagnose chILD, doctors may first need to rule out other diseases as the cause of a child's symptoms.
                
Early diagnosis of chILD may help doctors stop or even reverse lung function problems. Often though, doctors find chILD hard to diagnose because:
                
There are many types of the disease and a range of underlying causes
                
The disease's signs and symptoms are the same as those for many other diseases
                
The disease may coexist with other diseases
                
Going to a pediatric pulmonologist who has experience with chILD is helpful. A pediatric pulmonologist is a doctor who specializes in diagnosing and treating children who have lung diseases and conditions.
                
Medical and Family Histories
                
Your child's medical history can help his or her doctor diagnose chILD. The doctor may ask whether your child:
                
Has severe breathing problems that occur often.
                
Has had severe lung infections.
                
Had serious lung problems as a newborn.
                
Has been exposed to possible lung irritants in the environment, such as birds, molds, dusts, or chemicals.
                
Has ever had radiation or chemotherapy treatment.
                
Has an autoimmune disease, certain birth defects, or other medical conditions. (Autoimmune diseases occur if the body's immune system mistakenly attacks the bodys tissues and cells.)
                
The doctor also may ask how old your child was when symptoms began, and whether other family members have or have had severe lung diseases. If they have, your child may have an inherited form of chILD.
                
Diagnostic Tests and Procedures
                
No single test can diagnose the many types of chILD. Thus, your child's doctor may recommend one or more of the following tests. For some of these tests, infants and young children may be given medicine to help them relax or sleep.
                
A chest x ray. This painless test creates pictures of the structures inside your child's chest, such as the heart, lungs, and blood vessels. A chest x ray can help rule out other lung diseases as the cause of your child's symptoms.
                
A high-resolution CT scan (HRCT). An HRCT scan uses x rays to create detailed pictures of your child's lungs. This test can show the location, extent, and severity of lung disease.
                
Lung function tests. These tests measure how much air your child can breathe in and out, how fast he or she can breathe air out, and how well your child's lungs deliver oxygen to the blood. Lung function tests can assess the severity of lung disease. Infants and young children may need to have these tests at a center that has special equipment for children.
                
Bronchoalveolar lavage (BRONG-ko-al-VE-o-lar lah-VAHZH). For this procedure, the doctor injects a small amount of saline (salt water) through a tube inserted in the child's lungs. The fluid helps bring up cells from the tissues around the air sacs. The doctor can then look at these cells under a microscope. This procedure can help detect an infection, lung injury, bleeding, aspiration, or an airway problem.
                
Various tests to rule out conditions such as asthma, cystic fibrosis, acid reflux, heart disease, neuromuscular disease, and immune deficiency.
                
Various tests for systemic diseases linked to chILD. Systemic diseases are diseases that involve many of the body's organs.
                
Blood tests to check for inherited (genetic) diseases and disorders.
                
If these tests don't provide enough information, your child's doctor may recommend a lung biopsy. A lung biopsy is the most reliable way to diagnose chILD and the specific disease involved.
                
A lung biopsy is a surgical procedure that's done in a hospital. Before the biopsy, your child will receive medicine to make him or her sleep.
                
During the biopsy, the doctor will take small samples of lung tissue from several places in your child's lungs. This often is done using video-assisted thoracoscopy (thor-ah-KOS-ko-pe).
                
For this procedure, the doctor inserts a small tube with a light and camera (endoscope) into your child's chest through small cuts between the ribs. The endoscope provides a video image of the lungs and allows the doctor to collect tissue samples.
                
After the biopsy, the doctor will look at these samples under a microscope.