Sara Salvador, Department of Pulmonology, Vall d’Hebron University Hospital, Barcelona, Spain
Ana Villar, Department of Pulmonology, Vall d’Hebron University Hospital, Barcelona; Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain
Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease resulting from repeated inhalation of environmental antigens in genetically susceptible individuals. Its incidence and prevalence vary globally, influenced by geographic, occupational, and environmental factors. HP can present in non-fibrotic or fibrotic forms, the latter associated with a worse prognosis. Diagnosis involves a multidisciplinary approach, including clinical, radiological, serological, histopathological, and environmental data. Identification and elimination of the offending antigen are critical for management. Serological testing for specific immunoglobulin G, bronchoalveolar lavage lymphocytosis, and high-resolution computed tomography patterns are useful but have limitations. Specific inhalation challenge and lymphocyte proliferation tests are reserved for specialized centers. This article reviews current diagnostic strategies and discusses radiologic, bronchoscopy, and biopsy findings, emphasizing the role of antigen identification and classification into fibrotic or non-fibrotic forms to guide treatment and prognosis.
