What Is The Most Common Type Of Interstitial Lung Disease?

What Is The Most Common Type Of Interstitial Lung Disease?

Idiopathic Pulmonary Fibrosis is the most common type of interstitial lung disease. It is a debilitating and chronic disease characterized by a progressive decrease in lung function that makes breathing more difficult. The terminology “pulmonary fibrosis” refers to the healing of lung tissue, which causes a progressive decrease in lung function and as a consequence a respiratory insufficiency that worsens over time.

Diffuse interstitial lung diseases (DILD) constitute around 150 similar entities in which it is known as the causal agent in just a third of cases.

Idiopathic Interstitial Pneumonia

They constitute a group of diseases of unknown etiology with specific characteristics.

Idiopathic Pulmonary Fibrosis

It is a type of DILD with the histological manifestation of usual interstitial pneumonia (UIP). Idiopathic Pulmonary Fibrosis is the most frequent DILD. Its etiology is unknown.

It usually occurs after 50 years, with an insidious onset, in the form of progressive dyspnea and dry cough.

Non-specific Interstitial Pneumonia (NSIP)

Some years ago, it began to be observed that some biopsies of patients with diffuse interstitial lung disease did not fit any well-defined histological pattern of the classic interstitial pneumonia, this is called nonspecific interstitial pneumonia (NSIP).

Cryptogenic Organized Pneumonia (COP)

It constitutes an active fibrosing process that mainly affects distal bronchioles, alveolar ducts, and peribronchial alveoli, classically known as bronchiolitis obliterans organizing pneumonia (BOOP). The disease presents a subacute onset, with a progressive cough and dyspnea, often systemic symptoms such as fever, asthenia and weight loss. In some cases, the onset may be acute in the form of severe respiratory failure. BOOP may be caused by numerous causes and may be a finding in different entities, such as hypersensitivity pneumonia, nonspecific interstitial pneumonia, eosinophilic pneumonia or Langerhans cell histiocytosis.

For the diagnosis, it is required the association of the clinical-radiological data previously described with the histopathological demonstration of organized pneumonia in a lung biopsy sample.

The prognosis is good. Among the cases with the greatest risk would be the secondary to immunological disease, collagen, drugs, and environmental factors. For the treatment, glucocorticoids are administered at similar doses to those used in the NSIP.

Acute Interstitial Pneumonia (AIP)

The AIP is a rapidly progressive entity characterized by the presence of diffuse alveolar damage (DAD) in the lung parenchyma. The onset of symptoms is insidious, sometimes as a flu-like syndrome that can progress to severe respiratory failure requiring mechanical ventilation.

Respiratory Bronchiolitis-Interstitial Lung Disease (RB-ILD)

It is directly related to tobacco, it appears in smokers who smoke more than 30 packs per year. This is a histopathological lesion found in smoking patients, characterized by the presence of macrophages laden with a fine pigment inside the respiratory bronchioles. It is rarely symptomatic and is usually associated with a dysfunction of small airways. However, in rare cases, it occurs in the form of the interstitial disease with evident pulmonary symptomatology and abnormalities of respiratory and radiological function tests. That’s when we talk about the RB-ILD.

Desquamative Interstitial Pneumonia (DIP)

The name originated in the belief that the fundamental characteristic of this type of injuries was the “desquamation” of the epithelial cells. However, now it is known that it is really of aggregates of intraalveolar macrophages. It is considered as the advanced phase of the RB-ILD, due to its association with tobacco and the similarity of the anatomopathological findings.

Lymphocytic Interstitial Pneumonia (NIL)

It is characterized by the existence of interstitial lymphocytic infiltrates in the pulmonary parenchyma.

Many authors prefer to classify NIL in the epigraph of pulmonary lymphoproliferative disorders. This is so because in many cases it has been described the evolution towards lymphomas and NIL has gone to be considered then as a preneoplastic clinical presentation.

In fact, many cases described as NIL were probably non-Hodgkin’s lymphomas of low grade and phenotype B since its inception.

The distinction between NIL and a lymphoma, therefore, is difficult to do just applying routine techniques. It can present a subacute onset with a cough, progressive dyspnea (difficult breathing) and systemic symptoms (arthralgias which mean pain in the joints, fever, weight loss.)

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:October 19, 2018

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