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Biogenics Research Institute
Other Respiratory Tract Disorders
Hypersensitivity Pneumonitis
Idiopathic Intersitial Lung Disease

Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is a form of interstitial lung disease caused by inhalation of an organic antigen. The disease may present in several forms depending upon many factors including intensity and duration of exposure, the nature of the antigen and the susceptibility of the patient. Classic HP as currently defined has two dominant histopathological patterns on lung biopsy. About 70% will demonstrate granulomata formation and about 30% have a pattern of non-specific interstitial pneumonia. Recent publications have defined other histopathological patterns which may be seen that broadens the scope of this disease. Usually considered a rare disease, the current incidence of HP is being questioned and should be classified as an uncommon rather than a rare problem.  What was primarily an occupational disorder is now more commonly seen as induced by exposures in the home. There are more than 40 peer-review papers that describe hypersensitivity pneumonitis in home environments with approximately 30 mold antigens, in addition to birds, feathers, and mycobacterium. Causes of these contaminations are very varied, but revolve around excessive moisture within the caustive environment.


Diagnostic criteria currently utilized are helpful only for the acute presentation of the disease, but may actually impede the diagnosis of the subacute and chronic presentations.

Diagnosis is often difficult, particularly, with the subacute and chronic presentations. The patient history,  environmental history,  pulmonary function testing, laboratory tests, chest x-ray and  CT,  and lung biopsy are useful but not diagnostic. Avoidance-challenge techniques and long-term stability of the disease after remediation are more useful tools and observations to clearly define hypersensitivity pneumonitis. 

The goal of the attending physician and the patient is to remain non-progressive without any treatment after remediation.