Lung Cysts

A lung cyst, also known as a pulmonary cyst, is an air- or fluid-filled pocket or sac embedded within normal lung tissue. They are often identified via computed tomography (CT) scans.

Although it's not always known why lung cysts develop, different underlying conditions usually cause them to form. Certain lung cysts are treatable with medications, while others might require significant medical intervention, such as a lung transplant.

This article explains what lung cysts are, their causes, symptoms, diagnosis, and treatment.

Causes of Lung Cysts

Five primary lung diseases can cause lung cysts. These include:

• Lymphangiomyomatosis (LAM): LAM is a progressive disease that affects many body systems. LAM is associated with mutations in tumor suppressor genes. This association creates abnormal activation of cell growth, migration, and survival, which in turn, results in cysts forming throughout the lungs. LAM mainly affects women of childbearing age.
• Pulmonary Langerhans cell histiocytosis (PLCH): PLCH is caused when Langerhans cells (cells found throughout the body that help regulate your immune system) cluster and create nodules in the small airways and cysts throughout the lungs. PLCH is often diagnosed in adults under 40 and people who smoke cigarettes. PLCH occurs equally in males and females. Some people who have PLCH may be asymptomatic (without symptoms).
• Birt-Hogg-Dubé (BHD) syndrome: This is a rare genetic disease affecting the skin, lungs, and kidneys. BHD syndrome is usually diagnosed in a person's 40s or 50s and affects males and females equally. People with BHD syndrome also typically have skin lesions and renal (kidney) tumors.
• Lymphocytic interstitial pneumonia (LIP)/follicular bronchiolitis (FB): LIP is a rare disorder marked by lymphoid follicular hyperplasia (inflammation or enlargement from rapid cell growth, often an initial phase of cancer) throughout the lungs. Both of these disorders impact the lymphatic system of the lungs, so they are typically grouped together. LIP/FB usually affects women ages 40 to 70.
• Amyloidosis: Amyloidosis is extremely rare. People affected by it usually have a protein called amyloid deposited in extracellular (outside of the cell) spaces in an abnormal pattern throughout the lungs. However, pulmonary lung cysts due to amyloidosis are very rare. This disease tends to occur in a person's 60s.
  

Causes of Underlying Conditions

Causes of lung cysts depend on your underlying condition, which can include:

LAM: LAM can occur sporadically without a known cause or be a genetically linked disease in people affected by tuberous sclerosis complex. LAM is often misdiagnosed as asthma or chronic obstructive pulmonary disease (COPD).

PLCH: Cigarette smoke has been linked to PLCH as it activates Langerhans cells in the lungs.

BHD: BHD is inherited due to an autosomal dominant genetic defect. This means that one parent has a normal and mutated copy of a gene and has a 50% chance of passing it down to their child.

LIP/FB: LIP is often diagnosed in conjunction with other diseases, such as Sjögren's syndrome, rheumatoid arthritis, systemic lupus erythematous, or human immunodeficiency virus (HIV). These can all negatively affect the lung's lymphatic system, potentially resulting in LIP or FB. It is rare for LIP to occur from an unknown cause.

Amyloidosis: Amyloidosis is commonly associated with Sjögren's syndrome, LIP, or mucosa-associated lymphoid tissue (MALT) lymphoma. It is extremely rare for amyloidosis to be diagnosed without one of the associated disorders.

Symptoms

Symptoms vary depending on what type of lung cyst you have. Some may be asymptomatic, while others have progressive difficulty breathing. Symptoms may include the following:

• LAM symptoms include difficulty breathing, coughing up pink- or red-tinged sputum (saliva and mucus), spontaneous lung collapse (pneumothorax), and respiratory failure.
• PLCH symptoms can vary but often include shortness of breath, coughing, weight loss, fever, a collapsed lung, skin rash, and diabetes insipidus (an inability to regulate fluids properly).
• BHD is strongly correlated with spontaneous pneumothorax (lung collapse). Symptoms of a spontaneous pneumothorax include sudden onset of breathing difficulties and sharp, one-sided chest pain.
• LIP/FB includes cough symptoms and a progressive worsening of breathing difficulties.
• Amyloidosis symptoms do not present in everyone with the rare disease. The most common symptom for those with symptoms is dyspnea (sudden shortness of breath). Other symptoms include coughing, wheezing, coughing up red or pink-tinged sputum, and frequent bouts of pneumonia.
  

Diagnosis

Most of the time, lung cysts are identified by a CT scan. After completing a comprehensive physical examination and obtaining medical history, your healthcare provider, such as a pulmonologist (lung specialist), might recommend additional testing depending on the suspected cause of the lung cyst. Diagnostic testing for lung cysts includes:

• LAM: If LAM is suspected, additional testing might include taking samples (biopsies) of the cysts to be analyzed in a laboratory.
• PLCH: Additional testing for PLCH might include a rinse, also called a lavage, of the bronchi (airways) and alveoli (tiny sacs in the lungs) for abnormal cells, a lung tissue biopsy, or genetic testing and blood work. Individuals affected by PLCH often receive a pulmonary function test (PFT) every three to six months to identify any decline in lung function from increasing restriction of the lungs.
• BHD: Additional testing for BHD will likely include a lung biopsy and genetic testing. BHD is also associated with kidney cancer, so diagnostic tests may be given to assess kidney function and any cancer indications.
• LIP/FB: For LIP/FB diagnosis, a CT scan will typically indicate fewer lung cysts with random distribution throughout the lungs. A pulmonary function test may also be used; results usually indicate a restrictive respiratory pattern for people affected by LIP and an obstructive respiratory pattern for those with FB.
• Amyloidosis: Additional testing for amyloidosis includes lung biopsies to confirm protein deposits and additional blood work to ensure other diseases, such as Sjögren's syndrome, are not the cause of them.

Treatment

Treatment options vary depending on the cause of the lung cysts and can include:

• LAM: Medications, such as bronchodilators, help open the airways and ease breathing difficulty, while drugs like Rapamune (sirolimus) or Afinitor (everolimus) improve lung function. Due to the progressive nature of LAM, there is no cure, but medications like chloroquine, doxycycline, and Zocor (simvastatin), can help manage some of the symptoms. A lung transplant might be an effective option if you're experiencing advanced symptoms that medication cannot control.
• PLCH: Because PLCH is so rare, treatment is not standardized. Smoking cessation is one of the primary treatment interventions. Some people affected by PLCH who quit smoking have experienced complete remission. Others might require medications, such as a corticosteroid, to decrease inflammation and improve respiratory function. For those who do not respond to corticosteroid therapy, chemotherapeutic agents, such as Velban, Alkaban-AQ (vinblastine) or methotrexate, might be prescribed. Those experiencing a continuing decline in lung function might be considered for a lung transplant.
• BHD: BHD syndrome does not appear to impact lung function long term, so treatment options are minimal. If lung cysts caused by BHD syndrome cause frequent lung collapse or pneumothorax, pleurodesis (a surgical procedure) can help.
• LIP/FB: Treatment options for LIP/FB are primarily corticosteroids.
• Amyloidosis: Since lung cysts from amyloidosis are rare, no curative treatment options exist.

Summary

Lung or pulmonary cysts are the result of various disorders. The most common symptom is difficulty breathing; other symptoms depend on the underlying condition causing cysts. It is important to have a healthcare provider perform a comprehensive history and physical assessment and determine if a computed tomography (CT) scan or other diagnostic tests are needed for diagnosis.

Most treatment options focus on maintaining lung function and managing symptoms. Many causes of lung cysts do not have a defined cure and often progress and worsen over time. It's essential that your healthcare provider continually monitors your symptoms to ensure optimal lung health.

A Word From Verywell

Learning that you have a lung cyst can be difficult and worrisome, especially when it causes difficulty breathing. Speak to your healthcare provider to determine any underlying cause of breathing difficulties or lung cysts and to ensure prompt treatment.