Bronchiolitis obliterans

Editor-in-Chief: Kaochoy Saechao, MD, MPH

Overview
Bronchiolitis obliterans, Popcorn Workers' Lung or Diacetyl-induced Bronchiolitis Obliterans - DiBO, is a rare disease of the lung wherein the bronchioles are obliterated with fibrotic tissue.

Etiology
Bronchiolitis obliterans has many possible causes, including: collagen vascular disease, transplant rejection in organ transplant patients, viral infection (RSV, adenovirus, PCP, HIV, CMV), drug reaction, aspiration and complications of prematurity (bronchopulmonary dysplasia), and exposure to toxic fumes, including: diacetyl, sulfur dioxide, nitrogen dioxide, ammonia, chlorine, thionyl chloride, methyl isocyanate, hydrogen fluoride, hydrogen bromide, hydrogen chloride, hydrogen sulfide, phosgene, polyamide-amine dyes, and ozone. Additionally, the disorder may be idiopathic (without known cause).

Presentation
Bronchiolitis obliterans is a lung disease characterized by a fixed airway obstruction. Inflammation and scarring occur in the airways of the lung, resulting in shortness of breath and dry cough.

Diagnosis
Bronchiolitis obliterans patients should be seen by a board-certified Pulmonologist for accurate diagnosis.

Prognosis/treatment
This disease is irreversible and severe cases often require a lung transplant. Evaluation of interventions to prevent bronchiolitis obliterans relies on early detection of abnormal spirometry results or unusual decreases in repeated measurements.

Industrial inhalants
There is no consensus classification scheme for bronchiolitis subtypes. One author describes four specific subtypes as follows: cellular bronchiolitis, respiratory bronchiolitis, bronchiolitis obliterans and bronchiolitis obliterans with intraluminal polyps (proliferative bronchiolitis obliterans). There are many industrial inhalants that are known to cause bronchiolitis. Industrial workers who have presented with bronchiolitis:
 * nylon-flock workers
 * workers who spray prints onto textiles with polyamide-amine dyes
 * battery workers who are exposed to thionyl chloride fumes
 * workers at plants that use or manufacture flavorings, e.g. diacetyl butter-like flavoring