Clinical, Epidemiological, and Histopathological Features of Respiratory Involvement in Rheumatoid Arthritis.

Although by definition rheumatoid arthritis (RA) is an articular disorder, it is a systemic disease, and 18-40% of patients experience extra-articular manifestations (EAMs). The involvement of the respiratory system occurs in about 30-40% of RA patients, and in about 10-20% of them it represents the first manifestation of RA. A wide range of pulmonary manifestations are detectable in RA patients, including pulmonary parenchymal disease, pleural involvement, and airway and pulmonary inflammation. The clinical, radiological, and histological spectra of respiratory manifestations in RA reflect chronic immune activation, increased susceptibility to infection (often related to immunosuppressive medications), or direct drug. The type and severity of pulmonary involvement influence the prognosis, ranging from mild self-limiting conditions to severe life-threatening complications. Herein, we reviewed the various manifestations of respiratory involvement in RA, providing an overview on epidemiological, histological, clinical, and radiological data.