Am J Surg Path 2002;26:1567; Nejm 2001;345:517; Ann IM 2001;134:136

Cause:Unknown

Pathophys:Alveolitis is due to uncontrolled response of T cells to inflammation and/or B-cell production of IgG vs collagen? But inflammatory etiology in doubt. Possibly epithelial injury and abnormal wound healing.

Exaggerated release of platelet-derived growth factor by macrophages causes abnormal scarring/fibrosis (Nejm 1987;317:202)

Male > female; adults age 50-70 yr; rare, 7-10/100 000; associated w smoking

Sx:Dyspnea on exertion, nonproductive cough × 6+ mo

Si:“Velcro” or “cellophane” rales, clubbing, fever, cyanosis

Most fatal; mean survival = 5.5 yr (Nejm 1978;298:801); die of right heart failure (20%) or infection (80%)

r/o asbestosis; collagen vascular disease; BRONCHIOLITIS OBLITERANS (recurrent patchy pneumonia), may be work-related exposures (eg, butter fumes in microwave popcorn workers—Nejm 2002;347:330) w good prognosis and responds to steroids (Nejm 1985;312:152); and desquamative interstitial pneumonia

Lab:

ABGs:At rest show mild decrease in pO₂ and pCO₂; with exercise, marked decrease in pO₂

Hem:ESR elevated, crit usually normal despite decreased pO₂

Path:Lung bx shows fibrosis w some inflammatory component plus cellular hyperplasia of epithelium; hypertrophied bronchial muscle, endarteritis, and honeycombing in end stage

PFTs:Decreased volumes and diffusing capacity

Serol:Occasionally positive ANA, rheumatoid titer etc. (all are epiphenomena)

Xray:Chest shows reticulonodular infiltrate (fibrosis), esp at bases; spiral CT

Rx:

None good

Triple rx × 1+ yr, preserves lung function best (Nejm 2006;354:2229), w:

• Prednisone 0.5 mg/kg/d, up to 10 mg po qd after 6 mo
• Azothiaprine 2 mg/kg/d
• Acetylcysteine 600 mg po tid

Steroids alone may improve PFTs during acute phase but help only 11%

Lung transplant?