Boc

Bronchiolitis Obliterans
Synonyms	Obliterative bronchiolitis, Constrictive bronchiolitis
Pronounce	N/A
Specialty	N/A
Symptoms	Cough, shortness of breath, wheezing
Complications	Respiratory failure, pulmonary hypertension
Onset	Gradual
Duration	Long-term
Types	N/A
Causes	Inhalation of toxic fumes, viral infections, lung transplantation
Risks	Smoking, rheumatoid arthritis, organ transplantation
Diagnosis	Pulmonary function test, CT scan, lung biopsy
Differential diagnosis	N/A
Prevention	N/A
Treatment	Corticosteroids, immunosuppressive therapy, lung transplantation
Medication	N/A
Prognosis	Variable
Frequency	Rare
Deaths	N/A

Bronchiolitis Obliterans (BO), also known as Obliterative Bronchiolitis or Constrictive Bronchiolitis, is a rare and serious lung condition that affects the small airways, known as bronchioles. It is characterized by inflammation and fibrosis, leading to the obstruction of the bronchioles and resulting in significant respiratory impairment.

Etiology

Bronchiolitis Obliterans can be caused by a variety of factors, including:

• Inhalation of toxic fumes: Exposure to chemicals such as diacetyl, used in artificial butter flavoring, or other industrial fumes can lead to BO.
• Viral infections: Certain viral infections, particularly in children, such as adenovirus or respiratory syncytial virus (RSV), can result in BO.
• Lung transplantation: BO is a common complication following lung transplantation, often as a manifestation of chronic rejection.
• Autoimmune diseases: Conditions such as rheumatoid arthritis and systemic lupus erythematosus can be associated with BO.

Pathophysiology

The pathophysiology of Bronchiolitis Obliterans involves the inflammation and subsequent fibrosis of the bronchioles. The initial insult, whether chemical, infectious, or immunological, leads to an inflammatory response in the bronchiolar epithelium. Over time, this inflammation results in the proliferation of fibrous tissue, which narrows and eventually obliterates the bronchiolar lumen. This process impairs airflow and gas exchange, leading to the clinical manifestations of the disease.

Clinical Presentation

Patients with Bronchiolitis Obliterans typically present with:

• Cough: A persistent, non-productive cough is common.
• Shortness of breath: Patients often experience progressive dyspnea, especially on exertion.
• Wheezing: Wheezing may be present due to airway obstruction.
• Fatigue: Generalized fatigue and reduced exercise tolerance are frequently reported.

Diagnosis

The diagnosis of Bronchiolitis Obliterans is challenging and often requires a combination of clinical, radiological, and histological findings:

• Pulmonary function tests (PFTs): PFTs typically show an obstructive pattern with reduced forced expiratory volume (FEV1) and a decreased FEV1/FVC ratio.
• High-resolution CT scan: Imaging may reveal mosaic attenuation, air trapping, and bronchial wall thickening.
• Lung biopsy: A definitive diagnosis often requires a lung biopsy, which shows bronchiolar fibrosis and obliteration.

Management

Management of Bronchiolitis Obliterans focuses on controlling symptoms and slowing disease progression:

• Corticosteroids: These are often used to reduce inflammation, although their efficacy is variable.
• Immunosuppressive therapy: Agents such as azathioprine or mycophenolate mofetil may be used, particularly in post-transplant BO.
• Lung transplantation: In severe cases, lung transplantation may be considered, although BO can recur in the transplanted lung.

Prognosis

The prognosis of Bronchiolitis Obliterans varies depending on the underlying cause and the response to treatment. In post-transplant patients, BO is a leading cause of morbidity and mortality. Early detection and management are crucial to improving outcomes.

Prevention

Preventive measures include avoiding exposure to known chemical irritants and managing underlying conditions that may predispose to BO. In transplant patients, careful monitoring and management of rejection are essential.

See also

• Pulmonary fibrosis
• Chronic obstructive pulmonary disease
• Interstitial lung disease