Lung Abscess On Chest X-Ray And CT Scan

Lung abscesses are collections of pus in the lung.  They are diagnosed on imaging studies like chest X-rays and CT scans.  Patients who have underlying conditions and who are immunocompromised are most prone to developing abscesses.

Abscesses can arise from an infection of the lung like pneumonia.  They can also arise by spread of an infection from somewhere else in the body.   Abscess treatment is complex but often involves antibiotics, postural drainage and in some cases surgery.

What is a lung abscess?

A lung abscess is a collection of pus in the lung.  This often occurs as a complication of pneumonia or infection elsewhere in the body.

Symptoms of a lung abscess

The symptoms of lung abscess are not specific for abscess.  Symptoms can include fever, cough, chest pain.  More chronic abscesses can have milder symptoms including weight loss and fatigue.  Coughing up blood can occur as a result of an abscess involving a blood vessel in the lung.

How is lung abscess diagnosed?

Lung abscess is usually diagnosed using imaging studies like chest X-ray and CT.  There is often surrounding pneumonia.

What does lung abscess look like on chest x-ray?

A lung abscess is usually a round mass often with gas-fluid level.  We may see a surrounding pneumonia.

What does lung abscess look like on CT scan?

A round mass with gas-fluid level.  We can often see a surrounding pneumonia or infection somewhere else in the chest.

What else can look like lung abscess in radiology?

Masses with air-fluid levels are not specific for lung abscess.  Other possibilities include:


Both primary cancer and metastasis can develop gas inside.


This is an infection of pleural fluid.  Pleural fluid is located along the periphery of the lung,  There can be gas inside the pleural fluid and thickening of the pleura.  Distinction from abscess is important because empyemas are treated with drainage.

Cavitating pneumonia

This is a complication of pneumonia.  There is death of the lung tissue and liquefaction.

Infected lung cysts and bulla

These can have a similar appearance to lung abscess with air-fluid level.

Hiatal hernia

This is herniation of the stomach into the chest cavity.  On chest X-rays, this can have an air-fluid level just like an abscess.

What causes lung abscess?

They are most commonly a complication of pneumonia or aspiration.  They are most common in patients who have underlying conditions or are immunocompromised.  Certain organisms like staphylococcus predispose to abscesses.

Lung abscesses can also occur as a result of spread of infection from other places in the chest like the mediastinum or chest wall.  They can develop from blood borne infections, particularly in intravenous drug users.  Abscesses can develop as a complication of lung cancer when it obstructs the bronchus.

Is lung abscess dangerous?

Lung abscesses are dangerous and have high mortality rate.  They need prompt diagnosis and treatment.

What type of doctor treats lung abscess?

A lung specialist called a pulmonologist will be involved in the care.  In some cases, surgeons may also get involved.

Lung abscess treatment

Lung abscesses are treated with antibiotics and postural drainage of the involved lung.   Surgery and drainage is reserved for cases which do not respond to conservative treatment or have complications.

Lung abscess: summary

A lung abscess is a life threatening condition where a collection of pus forms in the lung.   This is often a result of a pneumonia but can occur from spread of infection elsewhere.

Imaging is used to diagnose lung abscess.  We will see a fluid filled mass often with air-fluid level.   Lung abscess is often treated conservatively with antibiotics and postural drainage.  More aggressive treatment with surgery is reserved for difficult cases.

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