Fibrotic hypersensitivity pneumonitis

Abstract

Hypersensitivity pneumonitis (HP), which is otherwise known as extrinsic allergic alveolitis, is a clinical syndrome characterized by diffuse interstitial involvement secondary to exposure to organic antigens. The diagnosis of HP relies on the clinical evaluation of a number of features, including a history of significant exposure to potentially causative antigens, physical examination, chest computed tomography (CT) scan appearances, bronchoalveolar lavage (BAL) lymphocytosis, and, in selected cases, histology. Now the entity is classified as nonfibrotic HP and fibrotic HP. Here we review the recent literature to highlight the new classification.