Seminars in respiratory and critical care medicine
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Nonspecific interstitial pneumonia (NSIP) is a complex disorder commonly associated with other conditions such as connective tissue diseases (CTDs) and environmental exposures. Although idiopathic NSIP has been recognized as a separate clinical entity, recent studies have suggested that a proportion of these cases have autoimmune features suggestive of underlying CTDs. The diagnosis of NSIP usually carries a better prognosis compared with idiopathic pulmonary fibrosis but has an unpredictable natural history. ⋯ There is a lack of consensus on the optimal management strategy of NSIP. Early clarification of the goals of therapy and close monitoring for the progression of disease is important across the spectrum of NSIP irrespective of its etiology. Although immunosuppressive and immunomodulatory agents are commonly used for severe and progressive disease, the therapeutic landscape of NSIP is constantly evolving as the role of newer agents such as antifibrotic therapies is being explored.
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Pulmonary Langerhans cell histiocytosis (PLCH) is a diffuse cystic lung disease that is strongly associated with exposure to cigarette smoke. Recently, activating pathogenic mutations in the mitogen-activated protein kinase pathway have been described in the dendritic cells in patients with PLCH and have firmly established PLCH to be an inflammatory myeloid neoplasm. ⋯ Smoking cessation is the cornerstone of treatment in patients with PLCH and can lead to disease regression or stabilization in a substantial proportion of patients. Further insight into the underlying molecular pathogenesis of PLCH has paved the way for the future development of disease-specific biomarkers and targeted treatment options directed against the central disease-driving mutations.
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Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder that has been recognized to involve virtually any organ in the body and typically manifests mass-like lesions (tumefactive). Although initial reports of this disease (autoimmune pancreatitis [AIP]) were described in the Japanese population, it has since been reported worldwide. It is most commonly seen in adults of middle age or older, more often men than women. ⋯ The diagnosis of IgG4-RD requires correlation of clinical, laboratory, imaging, and histopathologic features. Glucocorticoids are the first-line therapy but other options including B cell depletion are being investigated. IgG4-RD is generally associated with an indolent clinical course and most patients improve with glucocorticoid therapy.