Diffuse parenchymal lung diseases (DPLDs)

What are DPLDs?

Diffuse parenchymal lung diseases are a group of diseases that affect the pulmonary interstitium. Some of these conditions cause scars or swelling in the alveoli, damaging lung tissue and making it stiff, leading to difficulty breathing and reduced oxygen flow to blood. This condition is known as pulmonary fibrosis.

Causes of DPLDs can be classified into three categories:

• Idiopathic interstitial pneumonias when causes are unknown. The most common and prevalent is idiopathic pulmonary fibrosis (IPF).
• Known-cause interstitial pneumonias include those related to autoimmune and hereditary diseases (such as rheumatoid arthritis and scleroderma), those induced by medicines or radiotherapy, and those caused by external agents (tobacco, drugs, exposure to certain substances...).
• Unknown cause and granulomatous diseases such as sarcoidosis and alveolar microlithiasis.

Who is affected by DPLDs?

In Spain, there is a rate of 8 DPLD cases per 100,000 inhabitants. Idiopathic pulmonary fibrosis (IPF) is the most common, with a rate of 16 cases per 100,000 inhabitants and growing.

Those over 50 years old are the most affected group, although some DPLDs, such as sarcoidosis, can impact adults between 20 and 40 years old.

DPLDs symptoms

Primary symptoms of DPLDs are dyspnea or difficulty breathing and dry cough, but these diseases are hard to diagnose at an early stage and have a slow evolution. As the disease progresses and the lack of oxygen in the blood is more frequent, other symptoms might appear, such as cyanosis and the blue colour of the lips, feet, and hands.

Diagnosis involves several tests, from blood analysis to photography tests (x-rays, chest CT), spirometries, and, in some cases, invasive procedures such as bronchoalveolar lavage or lung biopsy.

Treatment of DPLDs

There are three key factors in treating DPLDs:

• Identifying the cause to avoid further exposure to the agent.
• In some cases, reducing swelling by giving anti-inflammatory drugs such as steroids or immunosuppressants.
• Treating the unforeseen difficulties of each specific case through oxygen therapy in case of respiratory failure or chest physiotherapy to restore the area.

As a last option, those DPLDs that lead to fibrosis with severe respiratory failures might require a long-term lung transplant.