Hypersensitivity pneumonitis (HP)- Global and Indian scenario

Abstract

Pulmonologists face a challenge in the diagnosis of HP which has multiple clinical phenotypes. In all newly diagnosed interstitial lung disease, HP should always be considered. The current guidelines classify HP into two main criteria based on clinical, radiological and pathological subtypes. They are acute/inflammatory HP and chronic/fibrotic HP. Patients who have a positive exposure history with a typical/classical pattern on HRCT and with BAL lymphocytosis, a diagnosis with high confidence can be made. Additional histopathological sampling should be done after multidisciplinary discussion in patients when an alternative diagnosis cannot be established. All efforts must be undertaken in patients of HP to identify the environmental inducers and eliminate the source to prevent and minimize exposure to the same and prevent the progression of the disease. Systemic corticosteroids still continue to remain the mainstay of treatment. Randomized clinical trials with existing and/new antifibrotic agents are required for effective management of patients with chronic HP. Lung transplantation offers some hope for patients with chronic progressive HP and patients should be evaluated early for the same