STEPTRACKERRESPIRATORY | PATHOLOGY + PHYSIOLOGY | HIGH-YIELD REVIEW

Restrictive Lung Disease

Stiff lungs or a stiff chest: small volumes with a normal-to-high FEV1/FVC — idiopathic fibrosis, pneumoconioses, drugs and chest-wall disease.

FOCUS ON
Restriction = ↓ TLC and FVC with FEV1/FVC normal or ↑. DLCO decides the site: low in interstitial disease, normal in chest-wall and neuromuscular disease. IPF = UIP pattern (subpleural, basal, honeycombing). Match each dust to its job, its lobe (coal and silica upper, asbestos lower) and its extra risk.
DISEASE
CAUSE · MECHANISM
FEATURES
CLUE
Restrictive physiology
Interstitial (parenchymal) vs extraparenchymal (chest wall, neuromuscular).
↓ TLC, ↓ FVC, FEV1/FVC normal/↑; ↓ DLCO only in interstitial disease
Obesity, kyphoscoliosis, ALS, myasthenia, GBS → normal DLCO
Idiopathic pulmonary fibrosis
Repeated alveolar epithelial injury (smoking, genetics incl. telomerase) → TGF-β → fibroblast proliferation.
UIP pattern: patchy subpleural basal fibrosis of different ages, fibroblastic foci, honeycombing
Older man: progressive dyspnea, dry cough, velcro crackles, clubbing · pirfenidone, nintedanib, transplant
Coal workers' pneumoconiosis
Inhaled carbon taken up by macrophages → fibrosis.
Upper lobes; simple nodules → progressive massive fibrosis
Caplan syndrome: RA + pneumoconiosis nodules
Silicosis
Quartz (sandblasting, foundries, mines, stone cutting) activates macrophages.
Upper lobes; silicotic nodules; eggshell calcification of hilar nodes
↑ TB risk (silica disrupts macrophage phagolysosomes); ↑ lung cancer
Asbestosis
Shipbuilding, roofing, plumbing, insulation.
Lower lobes; ferruginous bodies (iron-coated fibers, Prussian blue ⁺); calcified pleural plaques (most common lesion)
Lung carcinoma (most common cancer) > mesothelioma
Berylliosis
Aerospace, electronics, nuclear industries; beryllium-specific T cells.
Noncaseating granulomas (sarcoid-like); upper lobes
Steroid-responsive; ↑ lung cancer
Drug & radiation fibrosis
Bleomycin, busulfan, amiodarone, methotrexate, nitrofurantoin; chest radiation.
Interstitial pneumonitis → fibrosis
Check the drug list in any new ILD
Connective-tissue ILD
Systemic sclerosis, RA, dermatomyositis/polymyositis.
Often NSIP pattern (uniform, same-age fibrosis)
Anti-Scl-70, anti-Jo-1
Cryptogenic organizing pneumonia
Idiopathic or after infection, drugs, CTD.
Plugs of granulation tissue (Masson bodies) in alveoli and bronchioles
Subacute illness; responds well to steroids

Mechanism — injury to fibrosis

InjuryDust, drug, immune, unknown
→
Epithelial damage + macrophages
→
TGF-β, PDGFFibroblasts proliferate
→
Interstitial collagen↓ compliance, ↓ volumes
→
Thick barrier↓ DLCO → exercise hypoxemia → PH

Pneumoconioses at a glance

DUST
EXPOSURE
ZONE
KEY FINDING
Coal
Mining
Upper
Anthracotic macrophages; PMF; Caplan
Silica
Sandblasting, foundry
Upper
Eggshell nodes; TB risk
Asbestos
Shipyards, roofing
Lower
Ferruginous bodies, pleural plaques
Beryllium
Aerospace
Upper
Noncaseating granulomas

How it's tested

COMMON CONFUSIONCalcified diaphragmatic pleural plaques show asbestos exposure, but they are benign. They are not mesothelioma.
THE TRAPA sandblaster with silicosis develops a new cavitary lesion and night sweats. Silica impairs macrophage killing, so TB is the first concern.
YOUR APPROACHPFT pattern → DLCO (lung vs chest wall) → occupation and drugs → zone → biopsy/HRCT pattern (UIP, granulomas, ferruginous bodies).

If you see… think…

Older man, velcro crackles, clubbing, subpleural honeycombing → IPF
Fibroblastic foci with fibrosis of different ages → UIP pattern
Coal miner with RA and lung nodules → Caplan syndrome
Sandblaster with eggshell hilar calcification → silicosis
Shipyard worker with calcified diaphragmatic plaques → asbestos exposure
Golden-brown beaded rods in lung tissue → ferruginous bodies
Aerospace worker with noncaseating granulomas → berylliosis
Lung fibrosis after lymphoma chemotherapy → bleomycin
Restrictive PFTs with normal DLCO → chest wall or neuromuscular disease
FEV1/FVC 0.9, ↓ TLC, ↓ DLCO → interstitial lung disease