Abstract:

IgG4?related disease （IgG4?RD） is a chronic fibroinflammatory disorder with systemic involvement， predominantly affecting middle?aged and elderly males. Although the precise etiology and pathogenesis of the disease remain incompletely understood， its hallmark histopathological features include dense lymphoplasmacytic infiltration with IgG4?positive plasma cells， storiform fibrosis， obliterative phlebitis， and often increased numbers of eosinophils. While more than half of patients with IgG4?RD exhibit elevated serum IgG4 concentrations， this finding lacks specificity as it can also be observed in other conditions； furthermore， a subset of patients may present with normal serum IgG4 levels. Therefore， serum IgG4 elevation is not considered a definitive diagnostic criterion for this condition. The disease is characterized by its broad organ involvement frequently affecting the lymph nodes， salivary glands， lungs among others. The clinical and radiological manifestations of IgG4?RD exhibit a wide range of diversity， varying according to the specific organ involved. However， it generally demonstrates a favorable response to corticosteroid therapy while displaying a high propensity for relapse. Thoracic involvement in IgG4?RD presents an array of imaging findings encompassing abnormalities in the lungs， lymph nodes， pleura， chest wall， mediastinum， as well as large vessels such as the aorta and coronary arteries. Accurately differentiating IgG4?RD from malignancies， inflammatory conditions， and other autoimmune diseases poses a significant diagnostic challenge specifically for radiologists. This review aims to provide comprehensive insights into the pathophysiology， clinical characteristics， and thoracic imaging features of IgG4?RD with the ultimate goal of facilitating precise diagnosis and thorough evaluation of thoracic involvement。

Key words: IgG4?related disease, chest, computed tomography