Hypersensitivity pneumonitis

Abstract

Hypersensitivity pneumonitis (HP) is an inflammatory disease of the lungs and airways that develops in response to repeated inhalation of a wide range of aerosol antigens. The clinical picture and course of HP are highly variable and depend on such factors as the nature of the antigen, the intensity and duration of exposure to the antigen, as well as on the characteristics of the patient's immune response. The annual incidence of HAP is 1.28 -1.94 cases per 100 000. Currently, the diagnosis of HP is usually based on the characteristic clinical picture, high-resolution computed tomography (HRCT) data, bronchoscopy, lung biopsy, and evidence on the antigen. HRCT plays a central role in the diagnosis of HP. The most common finding on HRCT in HP is ground-glass opacities, which can be associated with centrilobular nodules and air trapping. In some cases, the fibrotic HP signs are very similar to those of idiopathic pulmonary fibrosis (IPF), and most changes are found in the lower regions and subpleurally. Therapy for HP usually includes avoiding exposure to the antigen, considering corticosteroids (CS) and/or immunosuppressive therapy to suppress the active inflammatory/immune response, and treating comorbidities. Nintedanib therapy in patients with progressive fibrotic HP results in a slower decline of lung function compared to placebo.