Medical News Today
7 July 2017
By Jennifer Huizen Reviewed by Judith Marcin, MD

Popcorn lung is a rare condition that causes airway scarring due to inflammation and eventually lung damage.

While treatments exist to limit and manage symptoms, currently there is no cure for popcorn lung, and it is considered life-threatening.

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Contents of this article:

What is popcorn lung
Symptoms
Causes
Does e-cigarette use cause popcorn lung?
Diagnosis
Prevention

What is popcorn lung?

Popcorn lung is characterized by the lung tissue scarring and becoming narrow. This can lead to breathing problems.

Popcorn lung is a rare medical condition that damages the bronchioles, the lung's smallest airways.

Over time, inflammation associated with popcorn lung causes lung tissues and airways to scar and narrow, causing breathing difficulties.

Popcorn lung gets its name from a chemical called diacetyl, which was once commonly used to give food products, such as popcorn, a rich, buttery flavor. In fact, the condition was first identified among popcorn factory workers who inhaled the chemical in the workplace.

Popcorn lung is also known as obliterative bronchiolitis, bronchiolitis obliterans, or constrictive bronchiolitis. Popcorn lung can be mistaken for a different condition called bronchiolitis obliterans organizing pneumonia (BOOP).

Symptoms

The symptoms of popcorn lung may be subtle and therefore easy to overlook, and the condition may be mistaken for other lung diseases. People with other respiratory conditions, especially chronic conditions such as asthma, may not be able to tell new symptoms apart from long-term complaints.

Besides diacetyl, there are a variety of other chemicals that can cause popcorn lung. Certain lung infections can cause it as well.

Symptoms typically occur within 2 to 8 weeks after infection or exposure to a chemical and slowly worsen over weeks to months. Some people may develop popcorn lung after transplant surgery, but it may take months to years to develop.

The most common signs and symptoms of popcorn lung include:

wheezing that is not related to another health condition, such as bronchitis or asthma
dry cough
shortness of breath or difficulty breathing deeply, especially with physical activity
unexplained exhaustion
rapid breathing
persistent skin, eye, mouth, or nose irritation if caused by a chemical

People should seek immediate medical attention whenever breathing becomes difficult, or if they experience chest pain or shortness of breath that leads to dizziness. People should also see their doctor if symptoms occur or chronic symptoms worsen.


Causes
Chemical damage to the lung tissues can cause popcorn lung, as can a few other factors. Although some hereditary conditions can cause popcorn lung, it is not considered an inheritable disorder.

Breathing in harmful chemicals, particles, or toxins can lead to popcorn lung. Food-flavoring fumes produced during the manufacture of candies, potato chips, popcorn, and dairy products, are major culprits.

Other examples include:

fumes from industrial or cleaning chemicals, such as ammonia or chlorine
nitrous oxide, also known as laughing gas
metallic fumes from construction activities, such as welding
industrial air particles, such as complex dust

Other factors that have been shown to cause or increase the likelihood of developing popcorn lung include:

certain viral or bacterial respiratory infections
having had a transplant
immune conditions, such as rheumatoid arthritis and hypersensitivity pneumonitis
certain drugs, such as penicillamine, 5-fluorouracil, and gold

Transplant surgeries may cause a condition called graft-versus-host disease, which occurs when the body rejects organ transplantation, particularly after lung, bone marrow, or stem cell transplants. This reaction can also lead to popcorn lung.

Does E-cigarette use cause popcorn lung?
E-cigarette liquid.
The chemicals found in e-cigarette liquid, known as "e-juice," may be a potential cause of popcorn lung.
According to the American Lung Association, using electronic cigarettes or vaping, particularly the flavored varieties, can cause popcorn lung.

Once the dangers associated with diacetyl were discovered in the early 2000s, the majority of popcorn producers stopped using the chemical. However, e-cigarette vapor has been proven to contain diacetyl.

A 2015 study of flavored e-cigarettes found that 39 out of 51 tested brands contained diacetyl. The same study concluded that most of these brands also contained the toxic chemicals acetoin and 2,3 pentanedione.

Manufacturers add diacetyl to the "e-juice" that is vaporized by e-cigarettes, most commonly to the strongly-flavored varieties. Diacetyl occurs in a wide range of different flavored e-cigarette products, ranging from vanilla to caramel and coconut.

E-cigarettes only came under the control of the U.S. Food and Drug Administration (FDA) in 2016. Changes to regulations may be required in the coming years as more research is carried out.

Diagnosis
A diagnosis of popcorn lung usually follows after a person has presented with the symptoms but has no other respiratory conditions.

Once a doctor suspects the condition, they will often perform a full exam and review the person's medical history. In particular, the doctor will look for possible causes, such as exposure to toxic fumes or infection.

Doctors may recommend further tests to confirm the diagnosis.

Commonly used tests include:

Bronchoscopy: using a small, flexible, lighted instrument to look inside the airways. Airway washes can be done during the procedure to collect cell samples.
Biopsy: removal of a portion of affected lung tissue for examination under a microscope.
Pulmonary function tests (PFT): breathing tests used to assess and monitor the progress of symptoms.
Computer tomography (CT) scans of the chest: detailed images of the lungs and airways can appear as a "mosaic" pattern.
Chest X-rays: may be used alongside other tests.

Treatment
Steroids.
Steroids may be prescribed to treat popcorn lung.
The lung tissue scarring caused by popcorn lung is irreversible. Also, there is no cure for the condition once it has developed and begun constricting the airways.

There are treatment options to manage or reduce symptoms and limit further lung damage, however.

It is crucial to recognize symptoms and diagnose popcorn lung early. As symptoms progress, the lung damage becomes more severe, and treatment becomes far more challenging.

The type of treatment recommended depends on the cause and severity of the case. If cases are due to chemicals or toxins, the individual should immediately leave the environment where exposure occurred and not return.

Treatment options for popcorn lung can include:

macrolide antibiotics for the treatment of bacterial respiratory infections may work in some individuals
steroids, specifically corticosteroids to lessen inflammation
immunosuppressive drugs that reduce the activity of the immune system and limit inflammation
supplemental oxygen
a medication called Singulair (montelukast), which blocks specific immune cells that produce inflammation
a lung transplant for very severe cases
The long-term outlook for many cases of popcorn lung depends on the cause and how fast the disease worsens. Cases due to rheumatoid arthritis can have an especially poor outcome. It is important to work with a doctor to develop a treatment plan that is specific to the cause and other underlying health problems.

Popcorn lung is also a leading cause of death associated with heart-lung and lung transplants. An estimated 50 to 60 percent of those who survive 5 years after lung transplantation experience the most severe cases of popcorn lung.

Prevention
The best way to prevent popcorn lung is to avoid lung damage. It is crucial to avoid the factors known to increase or cause the condition.

Ways to prevent the chances of developing popcorn lung include:

Not using e-cigarettes or other tobacco or vaping products, such as hookahs, especially those that use flavored products.
Avoiding areas or environments where it is possible to inhale chemicals or toxins, such as construction, demolition, and manufacturing sites.
Watching carefully for symptoms that may develop after organ transplants, especially lung, lung-heart, bone marrow, or stem cell transplants.
Wearing protective respiratory gear when exposed to environments where particles or toxins may be present in the air, such as deserts or heavily polluted areas.