Bronchiolitis is an inflammation of bronchioles. Bronchioles are small air passageways that lead to the air exchange units of the lung called alveoli.
Bronchiolitis has many causes, many of which are inflammatory or infectious in origin. Imaging studies such as X-ray and CT can identify manifestations of bronchiolitis.
What is bronchiolitis?
Bronchiolitis is an inflammatory disorder of the small airways in the lung that leads to the alveoli.
Acute bronchiolitis is usually an infection in children under 2 years old caused by a virus.
Chronic bronchiolitis refers to small airways disease in adults and can be caused by numerous conditions.
What causes bronchiolitis?
There are many causes of bronchiolitis such as:
Infectious: viruses, bacteria, TB, and fungus can cause infectious bronchiolitis. For example, in young children, respiratory syncytial virus can cause bronchiolitis
Hypersensitivity Pneumonitis: exposure to numerous external substances can cause inflammation and scarring of the small airways and lungs. These external substances can be microbes, proteins from animals, and inorganic particles like paints and other chemicals.
Bronchiolitis related to smoking: smoking cigarettes can lead to inflamed bronchioles and in more severe cases lung disease
Diffuse panbronchiolitis: This is a progressive inflammatory disorder of small airways which most commonly affects Asian populations.
Obliterative bronchiolitis: Both inflammation and scarring leads to narrowing and blockages of small airways. The condition is associated with medications, inflammatory bowel disease, lung transplantation and certain arthritides.
Aspiration bronchiolitis: This occurs after foreign particles get into the airways and cause inflammation of the bronchioles.
Symptoms of bronchiolitis
This depends on the cause of the bronchiolitis. Acute infectious bronchiolitis in kids may present with fever, cough, and trouble breathing.
Hypersensitivity Pneumonitis in adults may present with flu like symptoms after exposure to the external agent. Symptoms can also be more chronic after repeated exposure with cough, shortness of breath and weight loss.
How is bronchiolitis diagnosed?
A combination of clinical information, laboratory testing and imaging findings leads to a diagnosis of bronchiolitis.
What does bronchiolitis look like on x-ray?
Findings are non specific and may not be seen in some cases. Areas of air trapping and small nodules or hazy opacities may be seen.
What does bronchiolitis look like on CT scans?
We may see tree-in-bud opacities, bronchial thickening and mosaic attenuation in the lungs.
What else can look like bronchiolitis in medical imaging?
The findings of bronchiolitis are not specific, particularly when we see lung abnormalities associated with the airways/bronchiolar abnormalities. Both primary and secondary diseases can involve the bronchioles.
Is bronchiolitis dangerous?
It can be if there is trouble breathing or progressive lung disease.
What type of doctor treats bronchiolitis?
Acute bronchiolitis from infections may be treated by primary care providers or in emergency settings. Bronchiolitis which is chronic may be managed by lung specialists (pulmonologists).
The treatment depends on the underlying cause.
Acute infectious bronchiolitis in children is usually treated with supportive measures like hydration and fever control. More chronic bronchiolitis will be treated based on the cause.
Hypersensitivity pneumonitis will be treated by removing the precipitating agent.
Obliterative bronchiolitis may be treated with steroids like prednisone.
Bronchiolitis on chest x-ray and CT scan: summary
Bronchiolitis is a descriptive term indicating non specific inflammation of the small airways in the lung. This has many causes as outlined above.
The imaging findings are not specific for bronchiolitis in some cases. The diagnosis is made by combining clinical, laboratory testing and imaging findings. The treatment depends on the underlying cause.