Seminars in respiratory and critical care medicine
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Sarcoidosis is a multifactorial and polygenic disorder. Recently, several novel predisposing genes have been identified by genome-wide association studies, and fast progress in molecular technologies such as systematic and large-scale resequencing will aid the discovery of further risk loci and variants. ⋯ This may lead to the development of new hypotheses on pathomechanisms, which associate sarcoidosis with other granulomatous disorders but also with diseases with significantly different phenotypes. In the near future system, biology approaches will help unravel the differing and common features of these disorders and allow the development of new therapeutic strategies and tools to predict the course and response to treatment of individual patients.
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Semin Respir Crit Care Med · Jun 2014
ReviewCardiac involvement in sarcoidosis: evolving concepts in diagnosis and treatment.
Clinically evident sarcoidosis involving the heart has been noted in at least 2 to 7% of patients with sarcoidosis, but occult involvement is much higher (> 20%). Cardiac sarcoidosis is often not recognized antemortem, as sudden death may be the presenting feature. Cardiac involvement may occur at any point during the course of sarcoidosis and may occur in the absence of pulmonary or systemic involvement. ⋯ Although randomized therapeutic trials have not been done, corticosteroids (alone or combined with additional immunosuppressive medications) remain the mainstay of treatment. Because of the potential for sudden cardiac death, implantable cardioverter-defibrillators should be placed in any patient with cardiac sarcoidosis and serious ventricular arrhythmias or heart block, and should be considered for cardiomyopathy. Cardiac transplantation is a viable option for patients with end-stage cardiac sarcoidosis refractory to medical therapy.
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Semin Respir Crit Care Med · Jun 2014
ReviewClinical presentation of sarcoidosis and diagnostic work-up.
Sarcoidosis is a systemic disease of unknown cause characterized by the formation of immune granulomas which most often involve the lung and the lymphatic system. Sarcoidosis may encompass numerous different clinical presentations. Typical presentations often prompt a rapid diagnosis while in 25 to 50% of cases, diverse and less typical presentations may lead to delayed diagnosis. ⋯ The probability of diagnosis at presentation is variable from case to case and may often be reinforced with time. Some investigations are mandatory at diagnosis to assess organ involvement and disease activity. However, there are important variations in diagnostic work-up due to diverse expressions of sarcoidosis and differences in clinical practices among physicians.
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Semin Respir Crit Care Med · Jun 2014
ReviewCellular activation in the immune response of sarcoidosis.
Sarcoidosis is a chronic granulomatous disorder characterized by an accumulation of lymphocytes and macrophages in the alveoli. Ultimately, long-lasting, nontreated disease results in a distortion of the microarchitecture of the lower respiratory tract. Our current understanding of its pathogenesis is that several sequential immunological events finally resulting in granuloma formation are involved: (1) dependent on a susceptible genetic background described by a variety of functional polymorphisms (2) the exposure to one or several still elusive antigen(s), leads to (3) an activation of macrophages, (4) an attainment of T cell immunity against the antigen(s) mediated by antigen processing and presentation by macrophages, and finally to (5) induction of granuloma formation. ⋯ The important role of alveolar macrophages, T lymphocytes, regulatory T cells, and various cytokines/chemokines in orchestrating the induction, evolution, and immunoregulation of the sarcoid granulomatous/fibrotic lesions will be underscored. Although an etiological agent for sarcoidosis has not been identified, plausible "sarcoid antigens" including mycobacterial antigens such as mKatG or ESAT-6, antigens from Propionibacterium acnes, or even self-antigens will be discussed. It is possible that not one single causative agent exists but several germs, microbial products, or inorganic substances might induce pathogenetic mechanisms leading to a disease called sarcoidosis.
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Fluorodeoxyglucose (FDG), labeled with a positron emitting fluorine-18 ((18)F), is a synthesized glucose analogue and is well known for its application in a wide variety of clinical conditions such as cancer. Visualizing metabolic activity of inflammation is another application of FDG in positron emission tomography (PET). Here, active granulomas appear to have a high affinity for FDG, which is reflected in a high sensitivity of FDG PET imaging. ⋯ Moreover, FDG PET activity in lung parenchyma correlates with decrease of lung function values over time. Also in cardiac involvement in sarcoidosis, FDG PET is a promising technique complementary to magnetic resonance imaging, especially in guiding treatment. New developments, such as applications for quantitative organ-specific measurement, are proceeding and will probably enhance the clinical implementation of FDG PET in sarcoidosis.