Monthly Archives: May 2014

Obliterative Bronchiolitis

Bronchiolitis Obliterans – used by patho to refer to 2 distinct patterns of small-airway disease

1.  intraluminal polyps in small airways – bronchiolitis obliterans with organizing PNA or cryptogenic organizing PNA

2.  subepithelial inflammatory and fibrotic narrowing of bronchioles – obliterative bronchiolitis or constrictive bronchiolitis

“bronchiolitis obliterans syndrome” 

– occurrence of obstructive vent defect that occurs after transplantation, esp after solid-organ or bone marrow transplantation

Clinical presentation:

– progressive dyspnea and nonproductive cough over weeks to months

– obstructive pattern

Pathogenesis:

– injury and inflammation to small airway epithelial cells and subepith structures lead to fibroprolif, aberrant tissue repair, ineffective epith regen

– a final common pathway

Diagnostics:

PFTs: normal spirometry or slight decrease in FVC, dec FEV1 and reduced FEV1/FVC with poor response to inhaled bronchodilators

Lung volumes indicate air trapping, normal TLC and high RV

subset of patients has normal results on spirometry, a restrictive pattern with low FVC and normal FEV1/FVC or mixed obs/restriction.

DCO2 initially normal

Definition of Oblit Bronchiolitis after lung transplantation (1993, 2002), NIH 2005

CXR: normal; hyperinflation and inc linear or retic markings of airway wall thickening suggestive but nonspecific

HRCT: definitive noninvasive test, patchy decreased lung density with reduced vascular caliber (mosaic perfusion, mosaic attenuation)

advanced cases with dilatation and thickening of large airways characteristic of bronchiectasis

expiratory CT may facilitate early detection (shows air trapping)

characteristic is paucity of ground-glass opacities (seen in PNA or organizing PNA)

Associated Conditions:

– highest in RA

– exposure to inhaled toxins (SO2, HS)

– postinfectious (adenovirus, measles, mycoplasma)

– HSCT – usually within 2 yrs

– lung transplantation

Prognosis:

– natural history is highly variable

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