Pathology of Restrictive Lung Diseases Flashcards
key difference between sarcoidosis and hypersensitivity pneumonitis
although both are both chronic granulomatous diseases, the key difference is that in HP, there is significant interstitial inflammation in areas apart from the granulomas while in sarcoidosis, the inflammation is restricted to the granulomas and other lung tissue is normal
4 signs of restrictive lung disease?
- reduced lung compliance
- low FEV1 and FVC (but ratio remains the same)
- V/Q mismatch (although there is no obstruction in the main airways, smaller airways can be affected by pathology and result in reduced ventilation to that area)
- reduced gas transfer (issue with diffusion)
what is the main test used to see gas transfer and pulmonary microcirculation?
TCO and KCO test - shows movement of CO in/out of the lungs
TCO - transfer factor
KCO - transfer coefficient (TCO/unit alveolar volume)
general presentation of interstitial lung diseases
- clearer lung marking and intercostal shadow in CXR/CT
- type I resp failure
- progressive dyspnoea –> SOB
- heart failure
chronic and acute interstitial diseases
ACUTE:
- diffuse alveolar damage (DAD)
CHRONIC:
- sarcoidosis
- hypersensitivity pneumonia
- usual interstitial pneumonia
- others
disease progression of DAD
acute inflammation –> neutrophils –> destruction of capillary epithelium –> leaky vessels –> edema from exudates –> hyaline membranes (due to exudate deposition) –> interstitial inflammation –> interstitial fibrosis (stiff lungs)
mortality of DAD?
50% mortality
DAD usually happens as an exacerbation of another ongoing condition
causes of DAD
essentially anything:
- chemical/toxins/drugs
- radiation
- major trauma
- circulatory shock (cardiac arrest)
- infection, autoimmune disease
- idiopathic
describe sarcoidosis and its histology
- chronic multisystem granulomatous disorder (inflammation)
- common in young adults (females>males)
- disease of temperate (cold) climate
- no necrosis and little lymphatic infiltrate (indicating that it is not from an infective cause)
- epitheloid (macorophages) and giant cells
- fibrosis in some cases
presentation of sarcoidosis
- systemic upset
- SOB, cough
- abnormal CXR
- acute joint pain
- skin eruptions
- enlarged lymph nodes
- resp failure due to fibrosis
what other systems does sarcoidosis affect
- *lungs
- *lymph nodes
- skin, eyes, skeletal muscles
- liver
- spleen
- bone marrow
- salivary glands
investigations for sarcoidosis
- PMH
- CXR/CT
- serum calcium and ACE test
- blood findings
- histology test (Kveim test + Tuberculin test)
treatment for sarcoidosis
corticosteroids
describe hypersensitivity pneumonitis (HP)
- pathological reaction to inhaled antigens
- is an upper zone disease because of inhaled antigens
- combination of types 3/4 hypersensitivity reaction, granulomatous disease, and chronic inflammation
common antigens that causes HP
- thermophilic actinomycetes (micropolyspora faeni + thermoactinomyces vaulgaris)
- bird/animal proteins
- fungi
- chemical/toxins/drugs
acute and chronic presentations of HP
ACUTE:
- fever, myalgia (pain in muscles)
- dry coughs
- chills
- crackles, wheeze/tachypnoea
- antibody present
CHRONIC:
- fever, malaise, low-grade illness
- cough, SOB
- crackles + wheeze
- resp failure (type I)
describe usual interstitial pneumonitis (UIP)
- what HP will progress into if left untreated
- has the same prognosis as lung cancer, dead in 5 years
- progressive disease, end in honey combing
what will chronic interstitial diseases lead to at the end stage if left untreated?
end stage honey combing of lung
- this is most commonly caused by UIP
- affects elderly people < 50 yrs (M>F)
causes of UIP
it is mostly idiopathic, but often seen in:
- connective tissue diseases
- post infection
- drug reaction, exposure to asbestos
pathology of UIP
similar to interstitial chronic inflammation - pathology not specific to only UIP
- patchy interstitial chronic inflammation, different patches at different stages of inflammation
- type II pneumocytes hyperplasia
- vascular proliferation
- fibrosis
presentation of UIP
- cyanosis
- dyspnoea, cough
- basal crackles
- finger clubbing
- abnormal CXR (basal/posterior cysts + shadows of interstitial infiltrates)
- restrictive pulmonary function test and reduced gas transfer
