Flashcards in Interstitial and Occupational Lung Disease Deck (66)
What is interstitial disease?
Any disease affecting the lung interstitium (e.g. alveoli, terminal bronchi)
What are the effects of interstitial lung disease?
* Interferes with gas transfer
* Restrictive lung pattern
What are symptoms of interstitial disease?
* Breathlessness (mainly on exertion)
* Dry cough
What are types of interstitial lung disease?
What is chronic interstitial lung disease?
* Part of systemic disease
* Exposure to agent (e.g. drug, dust etc)
* Idiopathic - no known cause
What are 3 types of interstitial lung disease?
* Granulomatous diseases e.g. sarcoidosis, extrinsic allergic alveolitis
* Idiopathic pulmonary fibrosis (IPF)
* Non-specific interstitial pneumonia (NSIP)
What is sarcoidosis?
Granulomatous type 4 hypersensitivity disease of unknown cause
What systems are involved in sarcoidosis?
* Common: lungs, lymph nodes, joints, liver, skin, eyes
* Less common: kidneys, brain, nerves, heart
What is the pathology of sarcoidosis?
* Non-caseating granuloma of unknown aetiology
* Imbalance of immune system with type 4 (cell mediated) hypersensitivity
What is unusual about the prevalence of sarcoidosis?
Less common in smokers
What are clinical features of acute sarcoidosis?
* erythema nodosum
* bilateral hilar lymphadenopathy
* parotitis (inflammation of parotid glands)
What are the clinical features of chronic sarcoidosis?
* lung infiltrates (alveolitis)
* skin infiltrations
* peripheral lymphadenopathy
* Other organs: renal, myocardial, neurological, hepatitis, splenomegaly
What are differential diagnoses of sarcoidosis?
* Fungal infection
What are possible investigations for sarcoidosis?
* CXR (BHL) - primary test, often diagnostic
* CT scan of lungs (peripheral nodular infiltrate)
* Tissue biopsy (non-caveating granuloma)
* Pulmonary function (restrictive pattern due to lung infiltrates)
* Blood test - Agiotensin Converting Enzyme (ACE) as activity marker (NOT diagnostic test), hypercalcaemia, increased inflammatory markers)
What is the treatment for acute and chronic sarcoidosis?
* Acute: self-limiting condition - usually no treatment (oral steroids if vital organ affected e.g. impaired lung function, brain, eyes, heart, kidneys)
* Chronic: oral steroids usually needed, immunosuppression (e.g. azathioprine, methotrexate, anti-TNF therapy)
Why do CXR and pulmonary function have to be monitored for several years after sarcoidosis diagnosis?
Why is it important to treat uveitis due to sarcoidosis with steroid drops?
If don't control uveitis, anterior chamber of eye fills up with inflammatory fluid, leading to glaucoma and long term damage
What are non-caseating granulomas in sarcoidosis composed of?
Epithelioid histiocytes, multinucleate giant cells, lymphocytes, plasma cells, fibroblasts and collagen
What is extrinsic allergic alveolitis (hypersensitivity pneumonitis)?
Type II hypersensitivity (immune complex deposition) reaction to antigen - inflammation of the alveoli
What is another name for extrinsic allergic alveolitis?
What is the aetiology of extrinsic allergic alveolitis?
* Thermophillic actinomycetes (farmer's lung, malt workers, mushroom workers)
* Avain antigens (bird fancier's lung)
* Drugs (gold, bleomycin, sulphasalazine)
* No cause identified in 30% of cases
How is hypersensitivity reaction causes in extrinsic allergic alveolitis?
* Immune complexes form
* Circulate in bloodstream
* Become deposited in lungs causing hypersensitivity reaction
What are the 2 classifications of EAA?
Acute or chronic
What are the symptoms of acute EAA?
When do symptoms of acute EAA normally appear?
Several hours after antigen exposure (flu-like illness)
What are the clinical signs of acute EAA?
* Crackles (no wheeze)
* On CXR, will see widespread pulmonary infiltrates
What is the treatment for acute EAA?
* Antigen avoidance
What is chronic EAA?
Repeated low dose antigen exposure over years
What are the symptoms of chronic EAA?
Progressive breathlessness and cough