# Constrictive Bronchiolitis

https://www.nejm.org/doi/full/10.1056/nejmoa1101388

## Pathology

Membranous bronchioles develop mural smooth muscle hypertrophy or fibrous thickening with luminal narrowing.

## Presentation

Patient factors

- Burn pit exposures / Iraq service
- inhalation exposure to: Nitrogen dioxide, sulfur dioxide, inorganic dust, fly ash, and diacetyl (popcorn)
- Post-transplant
- Rheumatologic conditions

Non-specific respiratory symptoms and exercise limitation

## Workup

Imaging: shows air trapping on expiratory films in about 1/4. However, normal imaging findings occur in the majority due to the absence of alveolar disease

May have either obstruction or restriction on PFTs - though these are not required for the diagnosis 

Diagnosed on lung biopsy