RT Book, Section
A1 Gifford, Alex H.
A1 Enelow, Richard I.
A2 Grippi, Michael A.
A2 Elias, Jack A.
A2 Fishman, Jay A.
A2 Kotloff, Robert M.
A2 Pack, Allan I.
A2 Senior, Robert M.
A2 Siegel, Mark D.
SR Print(0)
ID 1122360968
T1 Hypersensitivity Pneumonitis
T2 Fishman's Pulmonary Diseases and Disorders, 5e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 978-0-07-179672-9
LK accessmedicine.mhmedical.com/content.aspx?aid=1122360968
RD 2024/04/24
AB Hypersensitivity  pneumonitis  (HP),  or  extrinsic  allergic  alveolitis,  is  a  spectrum  of  interstitial,  alveolar,  and  bronchiolar  lung  diseases  resulting  from  immunologically  induced  inflammation  in  response  to  inhalation  of  a  wide  variety  of  different  materials  that  are  usually  organic  or  low–molecular-weight  chemical  antigens  (or  haptens),  which  may  lead  to  irreversible  lung  damage.  Despite  the  terms  hypersensitivity  and  allergic,  HP  is  not  an  atopic  disease  and  is  not  associated  with  increased  IgE  or  eosinophils.  The  prevalence  of  HP  is  quite  variable  in  different  populations,  presumably  because  of  differing  intensity,  frequency,  and  duration  of  inhalation  exposure,  and  also  probably  due  to  host  factors  that  have  yet  to  be  identified.  Once  thought  to  be  a  relatively  rare  disease,  it  is  becoming  more  frequently  recognized  as  awareness  is  of  the  limitations  of  classical  diagnostic  criteria  has  increased.  Among  pigeon  breeders,  8%  to  30%  of  members  of  pigeon-breeding  clubs  who  participated  in  surveys  exhibited  evidence  of  HP,  so-called  pigeon  breeder’s  disease  (Fig.  58-1).  Among  farmers,  0.5%  to  5%  have  symptoms  compatible  with  HP,  so-called  farmer’s  lung  disease.  The  prevalence  of  symptoms  is  lower  in  farms  that  use  hay-drying  methods  that  decrease  exposure  to  the  responsible  antigens  and  increased  after  a  wet  summer  season.