Restrictive Lung Diseases

What causes decreased lung compliance in restrictive lung disease?

Interstitial lung disease → stiff lungs → ↓ TLC, ↓ all volumes.

What causes decreased respiratory muscle force in restrictive lung disease?

Neuromuscular disease → ↓ inspiratory capacity → ↓ TLC.

Radiologic hallmark of Interstitial Lung Disease

Abnormalities in interlobular septa > airways

What is honeycombing?

Clustered cystic airspaces at lung periphery → hallmark of advanced fibrosis (UIP/IPF).

Neuromuscular disease examples

ALS, Myasthenia Gravis, Guillain-Barré/CIDP, phrenic nerve injury.

Phrenic nerve injury diagnostic test

Abnormal sniff test with paradoxical diaphragm motion.

Musculoskeletal causes of restriction

Scoliosis, kyphosis, pectus excavatum, spinal compression fractures.

Obesity restrictive disease mechanism

Chest wall mass → ↓ lung volumes + hypoventilation.

PNEUMOCONIOSIS — Definition

Restrictive ILD caused by inhalation of inorganic dusts/fibers.

Particle size relevance in pneumoconioses

1–5 µm reach terminal respiratory unit

Pneumoconiosis treatment

PREVENT exposure — irreversible once fibrosis occurs.

Asbestosis exposure sources

Insulation, shipyards, brakes, refineries.

Asbestos timeline

5–10 yrs: BAPE(Benign Asbestos Pleural Effusion)

10-20yrs: Pleural plaques of Ca2+

20-30yrs: Bronchogenic lung cancer

30+ yrs: Asbestosis, Mesothelioma

Asbestosis pathology

Fibrosis + asbestos bodies (ferruginous bodies) required for diagnosis.»fibrosis of the lung caused by asbesto fibers

(macrophages eat asbestos but cant digest them so they stay in the respiratory tract where eventually they get inflammed and fibrotic tisuse forms)

Asbestosis radiology

Basilar fibrosis, honeycombing, pleural plaques.

Asbestos cancer associations

30+ yrs after exposure: Bronchogenic carcinoma (most common), mesothelioma (classic).

Silicosis exposure sources

Sandblasting, quarry work, construction, stonemasons.

Silicosis pathology + pathogenesis

Inhale silica dust>alveolar macrophages ingest but cant clear»forms Silicotic nodules (collagenous), upper-lobe predominant.

Silicosis radiology

Eggshell calcifications of hilar lymph nodes.

Silicosis TB risk

High — macrophage dysfunction+depletion increases TB susceptibility.

Silicosis treatment

Avoid exposure

Coal worker’s pneumoconiosis cause

Inhalation of coal dust + silica + ash»they get eaten by macrophages but not cleared. Form fibrotic nodules that can lead to progressive massive fibrosis

Coal worker’s pneumoconiosis pathology

Coal dust macules and silicotic nodules with surround pigmented macrophages

Coal worker’s pneumoconiosis treatment

Avoid exposure.

HYPERSENSITIVITY PNEUMONITIS — Definition

Immune-mediated reaction to inhaled organic antigens (Type III/IV).

Hypersensitivity Pneumonitis exposures

Farmer’s lung, pigeon breeder’s lung, hot-tub lung, bagassosis, maple bark stripper’s disease.

Hypersensitivity Pneumonitis acute presentation

4–12 hrs post exposure: fever, cough, dyspnea, ground glass opacities, centrilobular nodules.

Hypersensitivity Pneumonitis chronic presentation

Fibrosis, honeycombing, disabling disease.

Hypersensitivity Pneumonitis pathology

Poorly formed non-necrotizing granulomas + lymphocytic infiltrate.

Hypersensitivity Pneumonitis treatment

Avoid exposure to aggrevating agent as increased exposure can lead to fibrosis

Pneumonitis vs Pneumoconiosis

Pneumonitis=inhaled Organic( hay, bird stuff); Pneumoconiosis=inhaled INorganic (dust/coal/silica etc)

Granulomatous Inflammation in ILD causes

Hypersensitivity pneumonitis, sarcoidosis, drug-induced pneumonitis, infections (TB, atypical mycobacteria).

What is granulomatous inflammation?

Multinucleated giant cells with granulomas, usually non-necrotizing,

USUAL INTERSTITIAL PNEUMONIA (UIP) — Pathology

Temporal heterogeneity, fibroblastic foci, honeycombing.

USUAL INTERSTITIAL PNEUMONIA (UIP) radiology

Basilar + subpleural fibrosis with honeycombing.

USUAL INTERSTITIAL PNEUMONIA (UIP) clinical diagnosis + Tx

Idiopathic Pulmonary Fibrosis (IPF). Tx: with antifibrotic meds like nintedanib or pirfenidone to slow progression

Idiopathic Pulmonary Fibrosis patient profile

Late 50s–60s, former smoker, progressive dyspnea, clubbing.

Idiopathic Pulmonary Fibrosis treatment

Antifibrotics: nintedanib or pirfenidone (slow progression, do not reverse).

NONSPECIFIC INTERSTITIAL PNEUMONIA (NSIP) — Pathology

Temporal homogeneity, lymphocytic inflammation, NO honeycombing.

Nonspecific Interstitial Pneumonia Dx associations

Autoimmune disease (RA, lupus), drug-induced.

Nonspecific Interstitial Pneumonia treatment

Treat underlying condition (autoimmune, drug induced)

ORGANIZING PNEUMONIA (OP/COP) —

Masson bodies: plugs of loose connective tissue and fibroblasts in bronchioles/alveoli that don’t get shut down. Can lead to Dx: Post-Infectious Cryptogenic (COP)

Organizing Pneumonia (COP) clinical clue

“Pneumonia” not improving with antibiotics.

Organzing Pneumonia treatment

Systemic corticosteroids for 3–6 months.

DESQUAMATIVE INTERSTITIAL PNEUMONIA (DIP)

Pigmented alveolar macrophages filling airspaces. Srtrongly associated with smoking. No fibrosis

DESQUAMATIVE INTERSTITIAL PNEUMONIA (DIP) association? Tx?

Strongly linked to smoking. Smoking cessation

EOSINOPHILIC PNEUMONIA — Pathology

Eosinophils + macrophages filling alveoli

Acute eosinophilic pneumonia causes

Smoking, vaping, drugs

Chronic eosinophilic pneumonia causes

Idiopathic, hypereosinophilic syndromes, malignancy.

Loeffler syndrome

Transient eosinophilic pneumonia due to parasitic infection.

Eosinophilic pneumonia treatment

Systemic corticosteroids → rapid improvement.

Table

Key granulomatous ILDs (2 whats the difference)

Hypersensitivity Pneumonitis (poorly formed), sarcoidosis (well formed), infections.

Silo-Fillers Lung

Open silo and get huge burst of nitrogen inhaled, very low O2

Byssinosis (Cotton-workers lung)

Cotton ball dust direct torxic effect on airways via endotoxin»bronchospasm, bronchiolitis

Berylliosis, Dx?

Occupational exposure to beryllium which mimics sarcodiosis; Dx: with lymphocyte transformation test