Chronic hypersensitivity pneumonitis

Case contributed by Henry Knipe


Cough for months with increasing shortness of breath. Non-smoker.

Patient Data

Age: 60
Gender: Male

Reticular opacity and honeycombing in a mainly basal and peripheral distribution. Traction bronchiectasis in the bases. Widespread ground glass opacity. Gas trapping on expiratory images. Emphysematous changes at the lung apices. 

No pleural effusion. No lymphadenopathy. 

Bronchoalveolar lavage

MICROSCOPIC DESCRIPTION: The smears contain increased numbers of lymphocytes, neutrophils and eosinophils. There are no giant cells. No malignant cells are identified. 


  • Alveolar macrophages 34 (83-94%) 
  • Lymphocytes 46 (5-16%) 
  • Neutrophils 16 (1-6%) 
  • Eosinophils 4 (0-1%) 
  • Bronchial cells 0 (0-5%) 

CD4:CD8 = 0.99

DIAGNOSIS: Bronchoalveolar lavage RML: mixed inflammation.


MICROSCOPIC DESCRIPTION: The cryobiopsy contains lung parenchyma with preserved architecture. There is mild interstitial thickening with scattered lymphocytes. Peribronchiolar accentuation of the interstitial changes is not obviously seen. Scattered multinucleated giant cells are present in the interstitium and they contain cholesterol clefts and calcified deposits. No granulomas are identified. There is no evidence of organizing pneumonia. No eosinophilia is noted. The blood vessels show no evidence of vasculitis. No organisms are identified. The PAS stain shows no fungi. The Ziehl-Neelsen stain shows no acid fast bacilli. The Masson trichrome stain shows patchy mild interstitial fibrosis. There is no dense fibrosis or honeycombing. No evidence of malignancy is identified. In view of the clinical history, the overall features are most consistent with hypersensitivity pneumonitis. 

DIAGNOSIS: Right upper lobe cryobiopsy: Mild interstitial inflammation and fibrosis with giant cells, consistent with hypersensitivity pneumonitis.

Case Discussion

This patient had kept pigeons for many years, and the HRCT changes are consistent with the biopsy proven chronic hypersensitivity pneumonitis. The emphysematous changes at the lungs are thought to be from passive smoking (workplace exposure).

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