<prompt> Which of the following is associated with hypersensitive pneumonitisSilicosisAsbestosisByssnosisBerylliosis  <response>: Ans. is c Byssinosis None of the options mentioned are known to cause hypersensitivity pneumonitis but out of these Byssinosis is most closely related to Hypersensitivity pneumonitis.Hypersensitivity pneumonitis describes a spectrum of immunologically mediated, predominantly interstitial lung disorders caused by intense, often prolonged exposure to inhaled organic dusts and related occupational antigens.Etiology: Inhalation of organic dust most commonly spores of thermophilic fungi.Depending on the occupation or exposure of specific antigen numerous names have been given to hypersensitivity pneumonitis.Farmers lung - Thermophilic actinomycete on Mouldy hay or grain dust.Pigeon breeders lung - Proteins from serum excreta or feathers of the birds.Air conditioner lung or Humidifier lung - Thermophilic bacteria in heated water reservoirs.Also rememberHypersensitivity pneumonitis in a type III Type IV both hypersensitivity reaction. 