A common interstitial lung disease caused by hypersensitivity reactions of PULMONARY ALVEOLI after inhalation of and sensitization to environmental antigens of microbial, animal, or chemical sources. The disease is characterized by lymphocytic alveolitis and granulomatous pneumonitis.

Synonyms: Extrinsic Allergic Alveolitides, Pneumonitides, Hypersensitivity, Hypersensitivity Pneumonitides, Allergic Alveolitides, Extrinsic, Extrinsic Allergic Alveolitis, Pneumonitis, Hypersensitivity, Hypersensitivity Pneumonitis, Alveolitis, Extrinsic Allergic, Allergic Alveolitis, Extrinsic, Alveolitides, Extrinsic Allergic