Subacute hypersensitivity pneumonitis


Respiratory function tests were severely reduced as was his exercise tolerance.

Bronchoscopy and washing showed a lymphocytosis of 80%, the majority of the lymphocytes were T8, this is diagnostic of SAHP.

A follow-up CT after 19 days and a repeated lung function tests revealed a significant improvement.

The differential diagnosis here lies between:

The high lymphocyte count and a definite history of antigen exposure plus the response to removal from birds make SAHP the most likely diagnosis.

On HRCT, subacute hypersensitivity pneumonitis usually has the following features:

  • ground-glass opacity
  • centrilobular nodules
  • mosaic attenuation
  • expiratory air trapping 
  • mediastinal lymphadenopathy in about 50%