Bronchiolitis obliterans

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Bronchiolitis obliterans
Synonyms	Obliterative bronchiolitis, constrictive bronchiolitis
Pronounce	N/A
Specialty	Pulmonology
Symptoms	Cough, shortness of breath, wheezing
Complications	Respiratory failure, pulmonary hypertension
Onset	Gradual
Duration	Long-term
Types	N/A
Causes	Inhalation injury, lung transplant rejection, rheumatoid arthritis, viral infection
Risks	Smoking, exposure to toxic fumes
Diagnosis	Pulmonary function test, CT scan, lung biopsy
Differential diagnosis	Asthma, chronic obstructive pulmonary disease
Prevention	N/A
Treatment	Corticosteroids, immunosuppressive drugs, lung transplant
Medication	N/A
Prognosis	Variable, often poor
Frequency	Rare
Deaths	N/A

Obliterative bronchiolitis

Bronchiolitis obliterans is an inflammatory condition that affects the lung's tiniest airways, the bronchioles. In affected people, the bronchioles may become damaged and inflamed leading to extensive scarring that blocks the airways.

Epidemiology

Bronchiolitis obliterans syndrome is considered as a form of chronic allograft rejection after lung transplantation. The majority of lung transplant recipients who are long term survivors develop bronchiolitis obliterans syndrome. More than 50% of recipients will develop some degree of BO by 5 years post-transplant. The average time to diagnose BO is 16 to 20 months after lung transplant but has been reported as early as 3 months after transplantation. About 5% to 14% of Hematopoietic stem cell transplantation (HSCT) recipients also develop bronchiolitis obliterans syndrome which is pulmonary graft vs. host disease and can present several months to years later after transplantation.

Cause

Bronchiolitis obliterans may result from lung injury caused by a variety of different chemicals and respiratory infections. Inhaled chemicals known to irritate the lungs and lead to the condition include chlorine; ammonia; oxides of nitrogen or sulfur dioxide; welding fumes; or food flavoring fumes (such as diacetyl). Respiratory infections caused by respiratory syncytial virus, adenovirus, or Mycoplasma pneumonia have been linked with the condition.

Bronchiolitis obliterans can also be associated with rheumatoid arthritis and graft-versus-host disease following a lung or hematopoietic cell transplantation.

Inheritance

Bronchiolitis obliterans is not thought to be inherited. Most cases occur sporadically in people with no family history of the condition.

Signs and symptoms

Signs and symptoms of bronchiolitis obliterans generally develop approximately two to eight weeks after exposure to toxic fumes or a respiratory illness. Affected people may experience a dry cough, shortness of breath, and/or wheezing. Fatigue and wheezing in the absence of a cold or asthma may also be noted. Symptoms generally progress slowly over weeks to months. A physical exam may reveal decreased breath sounds and prolonged expiratory phase with or without wheeze usually both in inspiratory and expiratory phase. Rales may also be noted in some cases. Cases of bronchiolitis obliterans associated with Castleman’s disease may also have paraneoplastic pemphigus which may present with oral ulcers as well as lymphadenopathy.

Diagnosis

A diagnosis of bronchiolitis obliterans is often suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to support and confirm the diagnosis. These tests may include:

• Imaging studies (such as a chest CT scan)
• Pulmonary function tests
• Surgical lung biopsy (gold standard)

Treatment

Although there is no cure for bronchiolitis obliterans, treatment may help stabilize or slow its progression. The best treatment options and the effectiveness of the selected treatments vary based on the underlying cause and the severity of the condition. Medications often prescribed to people with bronchiolitis obliterans include certain types of antibiotics (called macrolide antibiotics), corticosteroids, and immunosuppressive drugs. In severe cases, lung transplantation may be recommended. Therapies such as cough suppressors or supplemental oxygen can also be given to manage the symptoms associated with the condition.

NIH genetic and rare disease info

• NIH info on Bronchiolitis obliterans

Bronchiolitis obliterans is a rare disease.

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