Interstitial lung diseases (ILD) are a group of lung disorders characterized by varying degrees of inflammation and fibrosis (scarring) occurring predominately in the interstitial space of the lung. The interstitial space is a lace-like network of tissue present in both the lungs and it supports the tiny air sacs called alveoli. It plays a vital role in the gaseous exchange between the blood vessels and the alveoli. At the initial Inflammatory stage, lung damage is reversible but once the fibrosis sets in it are often irreversible. If not diagnosed and treated early, the damage will become permanent.
Dr. V.Nagarjuna Maturu (Senior Consultant Pulmonologist, Yashoda Hospitals, Somajiguda, Hyderabad) says- Interstitial lung diseases are a common health problem and are often missed in their early stages. There are many causes for ILD. ILD can be the only manifestation of the disease when they are called idiopathic interstitial pneumonia (IIP). The most common of the IIPs is Idiopathic Pulmonary Fibrosis (IPF), which is usually seen in men above the age of 60, who smoke cigarettes or related tobacco products. Other causes for ILD include collagen vascular disease-associated ILD (CTD-ILD), drug-related ILD, and ILD associated with occupational and environmental exposures such as pneumoconiosis and hypersensitivity pneumonias. In India, exposure to pigeons or farm dust is an important cause of a type of ILD called Hypersensitivity pneumonitis (HP).
Most of the ILDs are characterized by progressive exertional breathlessness and persistent non-productive cough. Some of them might have a fever and may have symptoms associated with underline connective tissue disorder such as; systemic sclerosis-associated ILD (SSc-ILD) & rheumatoid arthritis-associated ILD. Breathlessness and dry cough are symptoms that may be seen in several other diseases. Hence, the diagnosis may be missed if we don’t suspect and evaluate for ILD in all persons presenting with unexplained cough or breathlessness.
High resolution compute tomography (HRCT) is the gold standard method for confirming the diagnosis of ILD. Once we diagnose the person to have ILD, the next step is to determine the type of ILD and the cause for ILD. This requires a multidisciplinary discussion (MDD) involving, chest physician, radiologist, and pathologist. In cases where the HRCT chest fails to confirm the exact pattern of ILD, a lung biopsy would be required. A novel technique for performing lung biopsies safely and as a daycare procedure is the “Cryo lung biopsy”, wherein the pulmonologist uses a special cryoprobe to freeze and remove small pieces of the diseases lung for examination. This has replaced the earlier surgical lung biopsy which was associated with more complications and a longer in-hospital stay.
Once the diagnosis of ILD is established, and the cause and pattern of ILD determined, treatment is initiated. Two groups of drugs that are used to treat ILD are – (a) anti-fibrotic agents: these drugs halt or slow the progression of fibrosis; (b) anti-inflammatory agents: these drugs shall reverse the ongoing inflammation and prevent fibrosis from setting in. The prognosis of ILD patients completely relies on an early and accurate diagnosis of ILD. For those patients where the disease is advanced and the person becomes oxygen-dependent, lung transplantation remains a treatment option.
Dr. M.Gangadhar Reddy (Consultant Pulmonologist, Yashoda Hospitals, Secunderabad) says- “Among all ILDs Hypersensitivity pneumonitis (HP), connective tissue disease related ILD and Idiopathic pulmonary fibrosis (IPF) are the most common ILDs. Hypersensitivity pneumonitis is immunologically mediated ILD that occurs in some people when they are chronically exposed to certain antigens, which leads to triggering of our own immune system causing acute or chronic inflammation, particularly to the interstitial space of the lung. If early intervention is not done, it could lead to chronic inflammation and ultimately irreversible scarring of the lung. Idiopathic pulmonary fibrosis is a chronic, progressive disease characterized by progressive fibrosis of lung parenchyma associated with significant morbidity. IPF is a rare disorder, occurs primarily in older adults and is more common in men than women. The exact cause of IPF is unknown but evidence suggest there are certain risk factors which could increase risk of development of IPF such as; smoking, gastro esophageal reflux disease or genetic polymorphism. Early diagnosis and treatment of IPF is very important for better prognosis of the patients. Connective tissue diseases (CTD) are a group of diseases with heterogeneous systemic features and lung involvement is observed commonly particularly in SSc-ILD and RA-ILD. CTD-ILD has become leading cause of mortality among the systemic sclerosis and rheumatoid arthritis patients. Regular screening for lung involvement and early diagnosis is utmost important for appropriate management.
Prognosis of ILD may vary, depending upon the subtype of ILD. If we regularly screen the high-risk patients, possibility of early diagnosis is high and early interventions could improve the outcome as well.
