Week 5/6 - B - Interstitial Lung disease (Sx, Ix, Tx)- Lobe predominance, I.P.F, Sarcoidosis, E.A.A, Pneumoconiosis Flashcards
This flashcard card set will dsicuss different conditions that affect the lung interstitium - it is useful to know whether these affect the upper or lower lobes of the lungs The upper and lower lobe distribution of certain pulmonary pathologies can be recalled using different mnemonics: What are the mnemonics?
Upper lobe or apical predominance - mnemonic = CASSETP Lower lobe or basilar predominance - mnemonic = BAD RASI
Name conditions that have an upper lobe predominance
Cystic fibrosis Ankylosing spondylitis Silicosis Sarcoidosis Extrinsic allergic alveolitis Tuberculosis Pneumoconiosis
Name conditions that have a lower lobe predominance
Bronchiectasis Aspiration pneumonia Drugs Rheumatoid arthitis Asbestosis Scleroderma / Sjorgens/SLE (connective tissue diseases) Idiopathic pulmonary fibrosis
Name the conditions for both upper and lower lobe predominance
Upper lobe predominance * Cystic fibrosis, Ankylosing spondylitis, Silicosis, Sarcoidosis, Extrinsic allergic alveolitis, Tuberculosis, Pneumonoconiosis Lower lobe predominance * Bronchiectasis, Aspiration pneumonia, Drugs, Rheumatoid,Asbestosis, Scleroderma/Sjorgen’s/SLE, Idiopathic pulomonary fibrosis
Interstitial lung diseases affect the pulmonary interstitium What makes up the pulmonary instertitium?
Pulmonary interstitium is a collection of support tissues within the lung that includes the alveolar epithelium, pulmonary capillary endothelium, and surrounding structures
What are the cells found in the lining of the alveolar epithelium?
Type 1 alveolar cells - simple squamous epithelium lining the surface Type 2 alveolar cells - these cells contain secretory granules known as lamellar bodies which fuse with the cell membrane and secrete surfactant
Lung intersitium - collection of support tissues within the lung that includes the alveolar epithelium, pulmonary capillary endothelium, and surrounding structures The lung interstitium can be divided into three zones, axial, parenchymal and peripheral What specifically is the lung parenchyma?
The lung paranechyma is specifically the portion of the lung concerned with gas exchange - alveoli, alveolar ducts and respiratory bronchioles
What is the difference between early and late stage interstitial lung disease?
In early stage ILD there is alveolitis - injury with inflammatory infiltrates to the alveoli In late stage ILD, progressive interstitial fibrosis of the lung can occur - scarring of the lung - irreversible
How are the causes of interstitial lung disease grouped? What is the most common cause?
Environmental/occupational causes * Extrinsic allergic alveolitis * Absestosis/silicosis/coal * Drugs * Infection eg TB Systemic disorders * Sarcodisos * Connective tissue diseass Idiopathic - Idiopathic pulmonary fibrosis - most common cause
What are clinical features usually seen in interstitial lung diseases? (we will discuss individual diseases shortly)
Clinical features * Dyspnoea on exertion * Non-productive praoxysmal cough - intermittent attacks of violent uncontrollable coughing
What are the standard tests carried out in interstitial lung diseases?
Usual tests which will be carried out regardless of the cause Pulmonary function tests - restrictive pattern * FEV1/FVC >70% * Total lung capcity and residual volume reduced DLCO (diffusion capacity of the lung for carbon monoxide( * Reduced CXR and/or high resolution CT
If the clinical history and imaging are not clearly suggestive of a specific diagnosis or malignancy cannot otherwise be ruled out, what investigation is carried out and how? * What are the two ways in which this investigation may be carried out in ILD? * Which is more reliable and generates more tissue?
If the clinical history and imaging fail to suggest a specific diagnosis or malignancy cannot be ruled out - a lung biopsy is usually carried out * Transbronchial biopsy - special forceps used at bronchoscopy * Transthoracic biopsy - more reliable and generates more tissue
What is the commonest interstitial lung disease? What causes it? Who is the disease more common?
Idiopathic pulmonary fibrosis is the most common intersitial lung disease- the cause of the disease is unknown Disease is more common in smokers
What can pulmonary fibrosis occur secondary to? What lobes do these diseases affect? Which drugs can cause pulmonary fibrosis? (name at least 3)
Pulmonary fibrosis can occur secondary to * connective tissue diseases * rhuematoid * asbestosis * drugs - eg methotrexate, amiodarone, nitrofuratoin, bleomycin These all tend to affect the lower lobes of the lungs
What are the 4C’s of fibrosis? What are the symptoms of IPF? What are the signs?
4Cs o f fibrosis - cough, clubbing, crackles (aka crepitations), cyanosis Symptoms of IPF - progressive breathlessness over several years, dry cough, OE - clubbing, bilateral fine inspiratory crackles, cyanosis if severe
We already know in chronic ILD, investigations show: * restrictive defect on PFT’s - reduced FEV1 and FVC with normal or raised FEV1/FVC ratio, * reduced lung volumes, * low gas transfer How are other causes of pulmonary fibrosis ruled out?
Rule out connective tissue diseases and rheumatoid by measuring ANA and rhuematoid factor Through history - rule out occupational exposure disease (pneumoconiosis) and environmental exposure disease (EAA) and drugs causing fibrosis
What is seen on CXR and CT scan in IPF? What is carried out if the results on CT are atypical?
CXR will show bilateral infiltrates and possible reticulo-nodular (web like nodular) shadows at the lung bases and periphery (also known as ground glass opacities)
HRCT scan - will show reticulonodular shadows bibasally and at periphery and honeycombing of thelung If results are atypical - LUNG BIOPSY
When describing the changes seen on CT or hsitopathology from a biopsy in IPF, what is the term used to describe?
The changes observed on biopsy and CT are referred to as usual intersittial pneumonia (UIP) - Usual intersitial pneumonia is the most common form of ILD - Since the medical term for conditions of unknown cause is “idiopathic”, the clinical term for UIP of unknown cause is IPF
What is sardcoidosis? What type of granuloma? What is a granuloma?
Sarcoidosis is a multisystem non-caseating granulomatous order of unkown aetiology defined by histological means A granuloma is an organised collection of T-lymphocytes and activated macrophages
Sarcoidosis can be split into acute and chronic What are the clinical features of acute sarcoidosis? What is acute sarcoidosis also known as?
Acute sarcoidosis aka Lofgren syndrome * Fever * Erythema nodosum - raised red lesions on lower extremities * Polyarthralgia * Bilateral hilar lymphdenopathy * Uveitis - blurred vision, red eye, photophobia * Parotitis
How does the pulmonary disease progress in acute to chronic sarcoidosis ie if on CXR?
Acute sarcoidosis begins with bilateral hilar lymphadenopathy Chronic has pulmonary infiltrates and finally fibrosis predominanntly in the upper lobe area
Extrinsic allergic alveolitis is also known as hypersensitivity pneumonitis What type of hypersensitivity and how does it occur?
E.A.A is a type III hypersensitivity reaction when antibody (IgG) binds to the antigen present in the lungs forming an immune complex - this immune complex gives rise to an inflammatory response leading to alveolar inflamamtion
Coal workers pneumoconiosis can be simple or complicated Simple is usually asymptomatic with CXR abnormality (round opacities in upper lobe) What are the symptoms and signs seen on CXR in complicated CWP?
Symptoms - suggestive of pulmonary fibrosis - eg progressive dyspnoea and non-productive cough CXR- progressive massive fibrosis in upper lobes - shown on left
There are few symptoms seen in simple silicosis What is the xray abnromality seen? (buzzword) What is seen in chronic silicosis?
CXR - egg shell calcification - seen on CXR to left Chronic silicosis shows a restrictive lung pattern and massive fibrosis
Abestosis is caused by inhalation of asbestos fibres It can cause the presence of pleural plaque Where does fibrosis/pleural plaque formation occur in patients with long term asbestos exposure? What cancers are the risk increased in a patient with absestos exposure?
Fibrosis and pleural plque formation occur predominanatly in lower lobes in patients with prolonged asbestos exposure - PLEURAL PLAQUES ON CXR Asbestos exposure increases the risk of bronchial adenocarcinoma and mesothelioma
