Hypersensitivity pneumonitis Flashcards
what is hypersensitivity pneumonitis also called
extrinsic allergic alveolitis(EAA)
what type of hypersensitivity reaction is involved in hypersensitivity pneumonitis
type III (IgG)
describe what causes the development of hypersensitivity pneumonitis
repetitive inhalation of organic allergens in sensitised individuals, causing a hypersensitivity reaction
what are the most common allergens that cause hypersensitivity pneumonitits
avian/bird proteins in droppings
thermophilic actinomycetes
fungi(e.g. aspergillus sp.)
drugs(e.g. gold)
what type of hypersensitivity pneumonitis is caused by avian/bird proteins in droppings
bird/pigeon fancier’s lung
what organic compound causes Farmer’s lung/sugarcane workers lung/mushroom workers lung
thermophilic actinomycetes
what type of hypersensitivity pneumonitis is caused by fungi
malt workers lung/cheese workers lung
what lung pathology arises from chronic hypersensitivity pneumonitis
pulmonary fibrosis
describe the symptoms of acute hypersensitivity pneumonitis(6-18 hrs after exposure)
cough, breathlessness, myalgia, fever
flu-like symptoms
describe the signs of chronic hypersensitivity pneumonitis
crackles, sometimes clubbing
describe the spirometry pattern seen in acute and chronic hypersensitivity pneumonitis
acute = reversible restrictive chronic = restrictive
describe what would be seen in a CXR for acute and chronic hypersensitivity pneumonitis
acute = wide spread pulmonary infiltrates chronic = pulmonary fibrosis, usually in lower zones
what would be seen on an HRCT scan for chronic hypersensitivity pneumonitis
ground glass attenuation in upper lobes
what is involved in treatment of acute hypersensitivity pneumonitis (4)
O2, steroids, antigen avoidance and anti-fibronytic therapy(e.g. pirfenidone) if fibrosis
what is involved in treatment of chronic hypersensitivity pneumonitis
removal of antigen, oral steroids
