Interstitial lung disease

What is interstitial lung disease also known as?

Diffuse parenchymal lung disease

What does ILD consist of?

•Consists of a diverse group of disorders that involve the pulmonary parenchyma and interfere with gas exchange.

The descriptive term "interstitial" reflects?

reflects the pathologic appearance in that the abnormality begins in the interstitium.

What are the unknown causes of ILD?

Idiopathic pulmonary fibrosis (most common)

Non-specific interstitial pneumonia

Acute interstitial pneumonia

What is idiopathic pulmonary fibrosis?

IPF is defined as a spontaneously occurring (idiopathic) specific form of chronic fibrosing interstitial pneumonia limited to the lung.

What is the most common of the spontaneously occurring diffuse parenchymal lung disease?

IPF

What is IPF associated with?

IPF is associated with the characteristic usual interstitial pneumonia (UIP) pattern on both radiology and histology: fibroblastic foci and architectural distortion (honeycombing).

What are known causes of ILD?

Occupational and environmental agents

Drug induced

Radiation induced

Secondary to connective tissues diseases (CTDs)

Occupational and environmental agents especially to what ?

•especially exposure to inorganic or organic dusts (silica, coal, asbestos).

Drug induced pulmonary toxicity such as?

•Nitrofurantoin (Antibiotic for urinary infections)

•Methotrexate (Drug for rheumatoid arthritis)

•Amiodarone (Drug for arrhythmias)

•Bleomycin (Chemotherapy for cancer)

What can ILD complicate?

•ILD can also complicate the course of most of the connective tissue diseases (eg, rheumatoid arthritis, systemic lupus erythematosus, scleroderma, mixed connective tissue disease etc.).

What are granulomatous ILD?

Sarcoidosis

What is sarcoidosis due to granulomatous ILD?

A multi-system disease characterised by granulomatous inflammation (non-caseating granulomas)

What are some miscellaneous causes of ILD?

Infective causes such as TB

Malignancy, lymphangitis carcinomatosis

Histocytosis X

What is usual interstitial pneumonia (UIP) pattern also known as?

clinically as idiopathic pulmonary fibrosis IPF

What is usual interstitial pneumonia due to?

is due to fibrosis with little or no inflammation

The other causes of ILD are predominated by?

by inflammation and develop fibrosis in later stages.

The interstitial damage and thickening results in?

decreased ability of oxygen to diffuse from the alveolus to the capillary resulting in reduction of diffusing capacity.

As fibrosis occurs and worsens architectural distortion of the lung, results in?

stiffening of the lung and restricted movement.

What are some characteristics of IPF lung?

Disrupted lung architecture

Inflammation

Dilated bronchi

Poor gas exchange

Irregular, distorted air sacs

Scarred, thickened, fibrotic alveolar walls

What is the difference between healthy lung and idiopathic pulmonary fibrosis?

The healthy lung is characterised by unscarred airways with thin‐walled alveoli and unimpeded gas exchange. Pathological features of the IPF lung include dilated bronchi, airway distortion, and thickened alveolar walls. Inflammation and fibrosis lead to impaired gas exchange within the alveoli

IPF (Usual Interstitial Pneumonia) histology is characterised by?

fibroblastic foci and architectural distortion called "honeycombing".

What are symptoms of ILD?

Progressive dyspnoea

Dry cough

What are symptoms of connective tissue disease?

•Fever, weight loss

•Eye symptoms due to inflammation, dry eyes

•Joint pain ( arthritis)

•Skin rash

What are symptoms of sarcoidosis?

Lofgren's syndrome most common symptomatic presentation:

•Fever

•Lymphadenopathy

•Arthralgia

•Tender nodules on the shin of the legs (erythema nodosum)

What are the important parts of history taking in ILD?

Drug history

Radiation history

Occupational history

Smoking history

Family history

Why is drug history important?

Detailed drug history to exclude possibility of drug-induced pulmonary fibrosis.

In some cases, lung disease may occur weeks to years after the drug has been discontinued

What are examples of drugs that could cause ILD?

•Nitrofurantoin (Antibiotic for UTIs)

•Methotrexate (Anti-inflammatory)

•Amiodarone (Anti-arrhythmic)

•Bleomycin (Chemotherapy for cancer)

Why is radiation therapy an important history factor?

Radiation-induced lung injury is directly related to the volume of irradiated lung and the cumulative dose of radiation.

Very important to enquire of previous malignancy that may have been treated with chemotherapy or radiotherapy.

What are examples of occupations that are linked w ILD?

•Bird racing

•Farming

•Coal mining

•Stone cutting

Why is smoking history important?

Smoking is an independent risk factor for idiopathic pulmonary fibrosis (IPF)

Uncommon types of ILD such as respiratory bronchiolitis interstitial lung disease (RBILD), desquamative interstitial pneumonia (DIP) and Langerhans' cell histiocytosis (LCH) occur almost exclusively in smokers

Why is familial history important for ILD?

A positive family history of respiratory disease should be sought.

*Both sarcoidosis and IPF can be familial, but this is rarer*

What are the 3C's of ILD clinical features?

Cough (dry), clubbing, crackles (fine)

What are the signs of ILD?

Tachypnea

Oxygen supplementation

Central cyanosis

Reduced chest expansion

Fine (velcro) end-inspiratory crepitations

Clubbing

Tar staining

Signs of cor-pulmonale (complications)

What are signs of cor-pulmonale?

Elevated JVP, loud P2, parasternal heave, tricuspid regurgitation, pulsatile hepatomegaly, lower limb pitting oedema

What other signs that are associated with ILD but not directly caused by it?

Signs of underlying connective tissue disease: Iritis/conjunctivitis, dry eyes, arthritis, skin rashes

Signs of sarcoidosis: erythema nodosum

What is important to keep in mind of clinical features of sarcoidosis?

Important to note that it can mimic many other conditions due to its systemic nature. It can be considered a differential diagnosis of many conditions.

What are some clinical features of sarcoidosis?

Lacrimal gland enlargement

Parotid gland enlargement

Nasal cutaneous sarcoid lesions (lupus pernio)

Cranial nerve palsy

Interstitial lung disease

Granulomatous liver disease

Phalangeal bone cysts

Skin plaques and nodules

Infiltration of scars

Arthropathies

Osteoporosis

Mononeuritis multiplex

Peripheral neuropathy

Pachymeningitis

Diabetes insipidus

Anterior uveitis

Lymphadenopathy

BHL

Splenomegaly

Cardiac arrhythmia

Erythema nodosum

What are crackles?

are interrupted non-musical sounds and result from collapse of peripheral airways on expiration.

What are crackles due to?

On inspiration, air rapidly enters these distal airways, and the alveoli and small bronchi open abruptly, producing the crackling noise

What are crackles similar to?

Similar to the sound heard when gently separating the joined strip of velcro on the blood pressure cuff (or jogging shoes)

What type of crackles are characteristic of pulmonary fibrosis?

Fine late inspiratory crackles

What can hypoxia lead to?

•Dyspnoea ( shortness of breath)

•Tachypnoea ( rapid breathing)

•Cyanosis - central + peripheral

Why does clubbing happen?

The exact cause of fingers clubbing is not fully understood. It may be produced by growth factors from megakaryocytes and platelets lodged in nail bed capillaries stimulating vascular connective tissue.

When clubbing occurs in the course of ILD, it is typically a -------- manifestation and suggests -------- ------- of the lung

late

advanced fibrosis

What is a complication of ILD and why?

Complications: Cor pulmonale is right ventricular (RV) dysfunction caused by advanced lung disease, such as ILD (or any other advanced lung disease causing chronic hypoxia - COPD classically)

What can the differential diagnosis of ILD be?

The differential diagnosis can be categorised by cause (see aetiology)

How else can ILD be categorised?

Zone it affects (upper or lower)

What are the upper zone diagnosis?

Inhaled insults (3 exceptions: sarcoid, radiation and ankylosis).

C oal

H istiocytosis

A ankylosis spondylitis

T B

S arcoidosis

What are the lower zone diagnosis?

Blood-borne insults (exception: asbestos)

R heumatoid arthirtis

A sbestos

S cleroderma

I diopathic pulmonary fibrosis

O ther: drugs

What drugs could cause a lower zone ILF?

Amiodarone

Methotrexate

Nitrofurantoin

Bleomycin

Other differential diagnoses of SOB and crackles heard on auscultation are?

•Bronchiectasis ( Crackles = Both inspiratory and expiratory , coarse, change with coughing)

•

•Chronic left heart failure ( Crackles = Mid-late inspiratory, coarse)

•

•Pulmonary oedema ( Crackles = Mid-late inspiratory, coarse)

What is ILD?

ILD is a heterogeneous group of disorders that are classified together because of similar clinical, physiologic, or pathologic manifestations.

What are the 3Cs of ILD?

Cough, Clubbing and Crackles that sounds like velcro!!

An important part of the physical examination of patients with an undiagnosed ILD is looking for?

extrapulmonary evidence of a systemic disease that might be associated with ILD