Internal Medicine

0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:40

842 Interstitial Lung Diseases

Imaging

■CXR: normal in 10%; diffuse interstitial patterns: reticulation

(lines/lace), ground glass, nodules, honeycombing, adenopathy

■CT:

➣Interstitial abnormalities, patterns as above

➣Dynamic exhalation demonstrates peripheral airway disease

(air-trapping/mosaic perfusion)

PFTs

■Lung volumes (reduced TLC, VC)

■Diffusing capacity (reduced)

■Spirometry (may show increased flow rates)

■ABG

■Exercise testing: to detect equivocal disease or establish baseline:

➣SaO2 during walking

➣Formal incremental exercise test with arterial line and exhaled

gas analysis

Lung Biopsy

■If history and imaging insufficient

■Bronchoscopic transbronchial biopsy:

➣Sarcoid, lymphangiitic carcinoma

➣Special studies:

Alveolar proteinosis: PAS stain

Eosinophilic granuloma:

EM – Langerhans cells

Stains: CD1A or S100

Lymphangioleiomyomatosis (LAM): smooth muscle stains

including HMB45

Eosinophilic pneumonia: BAL eosinophil >40%

■Open lung biopsy/video-assisted thoracoscopic (VAT) biopsy for

idiopathic interstitial pneumonia (IPF)

differential diagnosis

■Connective tissue diseases

■Medication-induced lung disease (furantoin, amiodarone, bleo-

mycin)

■Environmental lung disease:

➣Inorganic: asbestos, silica, beryllium, coal

➣Organic: bird breeder’s lung, farmer’s lung

■Idiopathic interstitial lung diseases require biopsy:

➣Idiopathic pulmonary fibrosis (IPF)