Diagnosis, Clinical Course and Treatment of Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is an inflammatory and fibrosing interstitial lung disease caused by inhaled antigens in susceptible individuals. Various environmental materials can serve as inciting agents of HP. Recent guidelines have defined typical radiologic and histopathologic findings of HP, classifying it into nonfibrotic and fibrotic HP categories, as this classification better correlates with clinical outcomes. Diagnosing HP poses challenges, necessitating multidisciplinary discussions based on clinical assessments and radiologic or histopathological features. The cornerstone of treatment lies in avoiding the causative antigen. Oral glucocorticoids serve as the initial treatment for symptomatic HP. Immunosuppressants may be employed in patients who do not respond to initial treatment, and antifibrotics could be considered for patients displaying progressive fibrosis. This review outlines the clinical features, diagnostic evaluation, and treatment of HP.