Interstitial lung disease

Dr Felix Woodhead

Consultant Respiratory Physician

Restrictive Defect

• “Small lungs” vs “Wheezy lungs” (obstructive)

• Intrinsic lung disease – abnormal radiology

– ↓TLco

• Extrathoracic restriction – normal radiology

– normal TLco

– ? ↑Kco (↓VA → TLco/VA ↑)

Extrathoracic Restriction• Soft tissues

– Obesity

– BMI not weight

• Muscles

– Diaphragm > intercostals

– Orthopnoea

– Sitting/lying FVC

• Thoracic cage

– Scoliosis > kyphosis

• Pleural thickening

Radiological patterns 1• Pleural effusions/mass

– Dense white with no air bronchograms

– Meniscus

– Beware the supine effusion

• Tumours

– Spiculated & single (primary) vs round & multiple (mets)

– May present as collapse

• Collapse

– Volume loss (shift of fissure/hilum)

– Obliteration of adjacent silhouette

Alveolar space filling (≡ consolidation)

• Fairly dense, with air bronchograms (patent airways)– Neutrophils ± microrganisms (pneumonia/organising

pneumonia)

– Eosinophils (eosinophilic pneumonia)

– Blood (pulm haemmorhage)

– Fluid (severe pulm oedema)

– Surfactant (alveolar proteinosis)

– Tumour (bronchoalveolar carcinoma – BAC)

Interstitial shadowing

• Less dense than consolidation, dots and lines on CXR (reticulonodular)

– Interstitial fluid (pulm odema)

– Trapped lymph (lymphangitis carcinomatosis)

– Inflammation/fibrosis • Interstitial lung disease

• Diffuse parenchymal lung disease

• Fibrosing alveolitis

• “pulmonary fibrosis”

An approach to chest radiographs• Normal or abnormal?

• If abnormal, how long?

• If consolidation ?pneumonia

– treat with antibiotics and repeat film 6-8/52

• If interstitial ?pulm oedema

– Treat with diuretics and repeat film in a few days

• Remember

– Not all LRTIs are pneumonia (bronchitis/bronchiectasis)

– Pulm oedema also seen with fluid resus and renal pts

• Long-standing shadowing ?diffuse parenchymal lung disease

CT radiology terminologyFleischner Society: Glossary of Terms for Thoracic Imaging

Radiology 2008 246 697-722

Consolidation Dense, white opacity, obliterating vessels

Ground glass Less dense, grey. Alveolar filling or fibrosis

Reticulation Thickened septal lines, usually indicates fibrosis

Honeycombing Cysts, usually basal and peripheral. Typical in IPF

Traction bronchiectasis

Airways in abnormal lung pulled apart. Indicates fibrosis

Secondary pulm lobule

Smallest part of lung surrounded by connective tissue. Central arteriole/bronchiole, periph venule/lymphatics/septal thickening

Mosaicism Patchy ground glass often of sec pulm lobules. Airways, vessels or interstitium

Myths about ILD

• ILD is always pulmonary fibrosis

• All ILD is the same

• IPF and CFA is the same

• There is no treatment for ILD

Respiratory Physiology

• Restrictive spirometry– FEV1/FVC ratio ≥ 70%

– FVC < 80%

– But may have normal levels

• Reduced TLC & RV

• Reduced TLco & Kco

• Serial change crucial

Interstitial Lung Disease caused by exposure to• Inorganic dusts

– Pneumoconiosis

– Asbestos, silica, coal dust

• Organic dusts

– Hypersensitivity pneumonitis (HP)

– Prev called Extrinsic Allergic Alveolitis (EAA)

– Birds, moulds etc etc

• Drugs

– Chemotherapeutic, methotrexate, amiodarone, others

– www.pneumotox.com

ILD associated with Rheumatological Disease• Rheumatoid (RF, anti-CCP)

• Systemic Sclerosis– Skin thickening ± internal organ fibrosis

– Anticentromere (ACA), anti-topoisomerase 1 (ATA, prev Scl-70)

• Idiopathic Inflammatory Myositis– Polymyositis (muscle) (Jo-1)

– Dermatomyositis (skin and muscle)

• SLE less commonly chronic ILD– acute pneumonitis & pleural disease more common

• Sjögren’s Syndrome – Ro, La (SSA,SSB)– Less commonly present with ILD

Idiopathic Interstitial Pneumonitis

• Cryptogenic Fibrosis Alveolitis (UK)

• Idiopathic Pulmonary Fibrosis (USA and elsewhere)

• Idiopathic disease usually does worse than secondary

• Idiopathic disease phenotypically very variable

• Idiopathic disease can be classified by surgical lung biopsy into the “IPs”

The “IPs” _ Interstitial Pneumonitis

UIP Usual The most common or usual form of IIP, characterises IPF

NSIP Non-specific Indeterminate

AIP Acute Rapid onset, Diffuse alveolar damage, ARDS

“Hamman-Rich Syndrome”

DIP Desquamative Alveoli full of ‘desquamed’ alveolar cells

Now recognised to be macrophages

smoking related

LIP Lymphocytic Seen in HIV and conective tissue disease

Esp Sjögrens

2002 ATS/ERS guidelines for Idiopathic Interstitial Pneumonia

Am J Respir Crit Care Med 2002 Nicholson et al Am J Respir Crit Care Med 2000

Common DPLDs

Idiopathic Pulmonary Fibrosis (IPF)• Not interchangeable term for IIP (a subtype of it)• ?most common IIP• Relatively poor prognosis• Median survival 2 ½ years• Histology

– Usual Interstitial Pneumonitis (UIP) when biopsied– Temporal and Spatial heterogeneity, not uniform

• Radiology– Typical features: basal, peripheral honeycombing, little GGO– May have any appearance– Typical features – don’t need to biopsy, atypical – biopsy helpful

IPF CXR

(Cryptogenic) Organising Pneumonia - COP

• Was also called Bronchiolitis-obliterans OP (BOOP)

• Histology– Buds of organising inflammatory material in terminal

bronchioles and airspaces

– Characteristic lesion is the Masson body

• Radiology– Consolidation ± GGO

– May fibrose (?overlap with NSIP)

• Usually responds well to steroids initially

Acute Interstitial Pneumonia

Hypersensitivity Pneumonitis• Prev called EAA• Variety of inhaled stimuli, can occur with drugs too• Check precipitins (IgG to allergens)• Histology

– Lymphocytic– Poorly-formed granulomata– Bronchocentric

• Radiology– Variety of appearances inc similar to IPF– Typical appearance mosaicism due to small airways involvement

• BAL may be lymphocytic

Non-specific Interstitial Pneumonitis• A holding diagnosis• Histology

– Appearances not typical for other diagnoses esp UIP– Temporally and spatially uniform in all samples– UIP in 1 and NSIP in 2 of 3 biopsies = UIP

• Radiology– Typically more GGO than IPF– Often fibrosis– Varied

• Clinical– Varied outcomes– May overlap with IPF, HP or COP?– Typical finding in CTD, many pts with idiopathic NSIP have CTD features

Smoking-related IIP• Respiratory Bronchiolitis

– Histological appearance in ‘healthy smokers’

– Pigmented macrophages in terminal bronchioles

– Clinical condition RB associated ILD (RBILD)

– RBILD radiology similar to HP

– BAL not lymphocytic

• DIP– ‘Desquamative’ due to erroneous belief cells shed into alveoli

– Diffuse collection of pigmented macrophages throughout alveoli

– Radiologically typified by diffuse GGO

• ?smoking related NSIP, Fibrosis and emphysema

Sarcoidosis• Often doesn’t need CT

• Scadding CXR stages of limited use

• CT appearances– Perihilar ‘Snow splats’

– Beading of fissures

– Lymphadenopathy

– May have atypical features

• Histology typical– Noncaseating granulomata

– Worth doing transbronchial and endobronchial biopsies

• BAL often lymphocytic

ILD hints

• CXRs tell you how long abnormality present and progress

• History esp CTD features vital (trumps biospy etc)

• CTs may be pathognomic

• BAL helpful in HP/sarcoid

• Phenotypically heterogeneous

• Expert advise needed and MDT

• Open biopsy may be helpful after expert advise

• Treatment uncertain, ?trials