From the Guidelines
Sarcoidosis is believed to result from an abnormal immune response to an unknown antigen in genetically susceptible individuals, with genetic factors, environmental triggers, and occupational exposures playing a role in its development. The disease is characterized by the formation of granulomas, which are collections of inflammatory cells, in various organs throughout the body. These granulomas can disrupt normal organ function and lead to symptoms.
Key Factors
- Genetic factors play a role, as sarcoidosis tends to run in families and is more common in certain ethnic groups, particularly African Americans and Northern Europeans 1.
- Environmental triggers may include infections (possibly mycobacteria or propionibacteria), inorganic particles like beryllium, and organic dusts.
- Occupational exposures, such as those experienced by firefighters, have also been linked to increased risk.
Immune Response
The immune response in sarcoidosis involves activation of T-lymphocytes and macrophages, leading to the release of inflammatory cytokines that contribute to granuloma formation. While the exact cause remains elusive, this complex interplay of genetic predisposition, environmental exposures, and dysregulated immune response appears to be responsible for the development of sarcoidosis. The clinical presentation of sarcoidosis exhibits a spectrum of manifestations ranging from the asymptomatic state to that of progressive and relapsing disease, with disease progression often leading to pulmonary impairment or, in some cases, death due to complications of progressive pulmonary fibrosis or from cardiac involvement 1.
From the Research
Causes of Sarcoidosis
- The exact cause of sarcoidosis is unknown 2, 3, 4, 5, 6
- Sarcoidosis is characterized by the formation of granulomas that can involve many organ systems, with the lungs and intrathoracic lymph nodes involved in more than 90% of cases 2
- The disease can affect virtually any organ and is unpredictable in its clinical course 3, 4, 6
- The severity of pulmonary sarcoidosis ranges from incidentally discovered radiographic abnormalities in asymptomatic patients to a chronic progressive disease that is refractory to treatment 6
Factors Associated with Sarcoidosis
- Genetic predisposition may play a role in the development of sarcoidosis, but the exact mechanisms are not well understood 5
- Environmental factors, such as exposure to certain chemicals or infections, may also contribute to the development of sarcoidosis, but the evidence is limited 5
- The disease is more common in certain populations, such as African Americans, but the reasons for this are not well understood 5
Organ Involvement
- The lung is the organ most commonly involved with sarcoidosis, with at least 90% of patients demonstrating lung involvement 2, 5
- Other organs that can be involved include the skin, eye, liver, and peripheral lymph nodes, with frequencies ranging from 10 to 30% 5
- Cardiac sarcoidosis is present in 25% of all sarcoidosis patients, but only causes clinical problems in 5% of them 5