Potential triggers are Mycobacterium tuberculosis and Cutibacterium acnes ( Propionibacterium acnes), but sarcoidosis is not an active infectious disease. Exposures included insecticides, mildew, mould, musty odours, and home central air conditioning. These included agriculture, health care, bird breeding, automotive industry, and middle/high school teaching. The ACCESS study (A Case Control Etiologic Study of Sarcoidosis), which recruited more than 700 incident cases and matched them with controls, did not show a clear cause, but suggested specific occupations and exposures that were more prevalent in patients with sarcoidosis. The phenotype involves an interaction between patient genotype and environmental factors.Īlthough the triggers for sarcoidosis are still unclear, certain environmental factors have been associated with the disease. Whether these not fully efficient responses are primary or secondary to local persistent antigen stimulation is unclear. The disease is polygenic, associated with specific human leukocyte antigens (class I: HLA-A, B, C class II: HLA-DP, DQ, DR). Familiar forms of sarcoidosis are reported in less than 10% of cases. This activates undifferentiated histiocytes into M2 phenotype macrophages, expansion and polarization of CD4+ lymphocytes towards Th1, Th17, and Th17.1 cells, impairment of T regulatory cell (Treg) function, and development of sarcoid granulomas with inflammation that releases a broad spectrum of mediators, including cytokines, chemokines, and oxygen radicals that are involved in aetiopathogenesis. These antigens are presumably sensed and processed by macrophages, but not fully cleared for unknown reasons, creating engulfment. Sarcoidosis is believed to develop in patients with genetic susceptibility after exposure to as yet unidentified antigens. Sarcoidosis is characterized by a T-helper response in which CD4 lymphocytes and activated macrophages accumulate in affected organs, resulting in the formation of granulomas. There is need for safe, easy, and reliable biomarkers to establish organ involvement and prognosis at the individual level. Close follow-up is also necessary, as sarcoidosis is a chronic disease with an unpredictable course. If sarcoidosis is suspected, an extensive work-up is required to establish organ involvement. However, the pulmonologist usually has a key role in diagnosis and management, because the lungs and thoracic lymph nodes are the organs most commonly involved. Alternative diagnoses are always possible and should be borne in mind.Īs sarcoidosis is a systemic disease, a multidisciplinary approach is suggested for best outcomes. The diagnosis of sarcoidosis relies on a compatible clinical and radiological picture, biopsy evidence of non-caseating, non-necrotizing granulomas, and exclusion of other similar diseases. Early diagnosis is challenging, and thus diagnosis is often delayed. Sarcoidosis is a relatively uncommon disease with heterogeneous onset and manifestations, which are often shared with other more common diseases.
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