Diagnosis of Hypersensitivity Pneumonitis in Adults

Publication Date: August 1, 2020

Key Points

Key Points

  • Hypersensitivity pneumonitis (HP) must be considered in the differential diagnosis for patients with newly identified interstitial lung disease (ILD).
  • This guideline committee categorized HP into two clinical phenotypes—nonfibrotic and fibrotic HP—and made separate recommendations for each.

For patients with clinical and radiographic manifestations suggestive of nonfibrotic HP (i.e., patients without radiological and/or histopathological evidence of fibrosis), the guideline committee:
  • makes no recommendation or suggestion for or against the use of a questionnaire to identify potential HP inciting agents and sources. Instead, the guideline committee recommends development and validation of a questionnaire.Remark: Pending the availability of a validated questionnaire, the guideline committee advocates that clinicians take a thorough history to identify potential exposures and sources in the patient's environment that are known to be associated with HP.
suggests performing serum IgG testing that targets potential antigens associated with HP. (S, VL)
620
recommends obtaining bronchoalveolar lavage (BAL) fluid for lymphocyte cellular analysis. (C, VL)
620
suggests transbronchial forceps lung biopsy. (S, VL)
620
makes no recommendation or suggestion for or against transbronchial lung cryobiopsy.
suggests surgical lung biopsy only when all other diagnostic testing has not yielded a diagnosis. (S, VL)
620

For patients with clinical and radiographic manifestations suggestive of fibrotic HP (i.e., patients with radiological and/or histopathological evidence of fibrosis), the guideline committee:
  • makes no recommendation or suggestion for or against the use of a questionnaire to identify potential HP inciting agents and sources. Instead, the guideline committee recommends development and validation of a questionnaire.
    Remark: Pending the availability of a validated questionnaire, the guideline committee advocates that clinicians take a thorough history to identify potential exposures and sources in the patient’s environment that are known to be associated with HP.
suggests performing serum IgG testing that targets potential antigens associated with HP. (S, VL)
620
suggests performing serum IgG testing that targets potential antigens associated with HP. (S, VL)
620
makes no recommendation or suggestion for or against transbronchial forceps lung biopsy.
suggests transbronchial lung cryobiopsy. (S, VL)
620
suggests surgical lung biopsy; this recommendation is intended to apply when all other diagnostic testing has not yielded a diagnosis. (S, VL)
620

Diagnosis

...Diagnos...

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...ith newly identified ILD whose differ...


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...Sources of Antigens Known to Cause HPH...


...2. Recommended Chest HRCT Scanning Para...


...ble 3. Radiological Terms for Heterogenous Lung A...


...HRCT Scan Features of the Nonfibrotic HP PatternHa...


Figure 1. “Typical hypersensitivity pneumo...

...fibrotic typical HP pattern is characterized...

Table 5. Chest HRCT Scan Features of th...

...2. Three-density Patt...

...olution computed tomography (A) inspirat...

...e 6. Histopathological Criteria for the...

...3. Surgical Lung biopsy Specimen f...

...A) Low-magnification photomicrograph...

...C) Poorly Formed Granulomas Characteristic of...

...magnification photomicrograph illustrating isola...

...5. Photomicrographs of Surgical Lung Biops...

...Scanning magnification view showing multiple sect...

...Hypersensitivity Pneumonitis Diagnosis Base...

...igure 7. Diagnostic Evaluation of Possi...