The HRCT features of extrinsic allergic alveolitis

Thomas E. Hartman

Research output: Contribution to journalReview articlepeer-review

28 Scopus citations


Exposure to organic dusts can produce an immune-mediated inflammatory response in sensitized individuals. The pulmonary disease caused by this response has been called extrinsic allergic alveolitis (EAA) or hypersensitivity pneumonitis. The clinical phases associated with this process have been termed acute, subacute, and chronic. There are corresponding imaging findings that are characteristic of each of these phases, although there is some overlap between the phases. The acute phase is characterized by confluent opacities that may mimic infection or edema. The subacute phase is characterized by centrilobular nodules, areas of ground-glass attenuation, a mosaic perfusion pattern, and air trapping on expiratory imaging. The chronic phase is characterized by subpleural irregular linear opacities with associated architectural distortion. Honeycombing may sometimes also be present. In the acute and subacute phases, the disease is predominantly in the lower lungs, whereas in chronic EAA the findings are predominant in the mid to upper lungs. Although the high-resolution computed tomography findings individually are nonspecific, the combination of the findings coupled with the distribution of the findings can often narrow the differential or allow a presumptive diagnosis of EAA to be made.

Original languageEnglish (US)
Pages (from-to)419-425
Number of pages7
JournalSeminars in Respiratory and Critical Care Medicine
Issue number4
StatePublished - Aug 2003


  • Air trapping
  • Centrilobular nodules
  • Extrinsic allergic alveolitis
  • High-resolution CT
  • Mosaic perfusion

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


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