In nonpersistent disease,  a strong genetic association exists with HLA DR3-DQ2. Cardiac sarcoid has been connected to tumor necrosis factor alpha (TNFA) variants. Infectious agents
Several infectious agents appear to be significantly associated with sarcoidosis, but none of the known associations is specific enough to suggest a direct causative role. The major implicated infectious agents include: mycobacteria, fungi, borrelia, and rickettsia. A meta-analysis investigating the role of mycobacteria in sarcoidosis found it was present in 26.4% of cases, but they also detected a possible publication bias, so the results need further confirmation. Mycobacterium tuberculosis catalase-peroxidase has been identified as a possible antigen catalyst of sarcoidosis. The disease has also been reported by transmission via organ transplants. A large epidemiological study found little evidence that infectious diseases spanning years before sarcoidosis diagnosis could confer measurable risks for sarcoidosis diagnosis in the future. Autoimmune
Association of autoimmune disorders has been frequently observed. The exact mechanism of this relation is not known, but some evidence supports the hypothesis that this is a consequence of Th1 lymphokine prevalence. Tests of delayed cutaneous hypersensitivity have been used to measure progression. Pathophysiology
Granulomatous inflammation is characterized primarily by the accumulation of macrophages and activated T-lymphocytes, with increased production of key inflammatory mediators, tumor necrosis factor alpha (TNF), interferon gamma, interleukin 2 (IL-2), IL-8, IL-10, IL-12, IL-18, IL-23 and transforming growth factor beta (TGF-β), indicative of a T helper cell-mediated immune response.
Medications such as methotrexate, chloroquine, or azathioprine may occasionally be used in an effort to decrease the side effects of steroids. The risk of death is  1–7%. The chance of the disease returning in someone who has had it previously is less than 5%.In 2015, pulmonary sarcoidosis and interstitial lung disease affected 1.9 million people globally and they resulted in 122,000 deaths. It is most common in Scandinavians, but occurs in all parts of the world. In the United States, risk is greater among black  people as opposed to white people. It usually begins between the ages of 20 and 50. It occurs more often in women than men. Sarcoidosis was first described in 1877 by the English doctor Jonathan Hutchinson as a non-painful skin disease. Signs and symptoms
Sarcoidosis is a systemic inflammatory disease that can affect any organ, although it can be asymptomatic and is discovered by accident in about 5% of cases. Common symptoms, which tend to be vague, include fatigue (unrelieved by sleep; occurs in up to 85% of cases ), lack of energy, weight loss, joint aches and pains (which occur in about 70% of cases), arthritis (14–38% of cases), dry eyes, swelling of the knees, blurry vision, shortness of breath, a dry, hacking cough, or skin lesions. Less commonly, people may cough up blood. Sarcoidosis is also accompanied by psychological distress and symptoms of anxiety and depression, which are also associated with fatigue.