HomePatientsLung Disease Week at the ATS2019Sarcoidosis ▶ General Information about Sarcoidosis
General Information about Sarcoidosis


Sarcoidosis is an inflammatory condition with an etiology that remains elusive. While the disease can affect any organ system, it most commonly presents in the lung. Epidemiologic studies have identified race and certain gene alleles related to immunity and immune cell dysfunction as risk factors for the disease. Clustering of the disease in specific geographical areas such as the United States and Scandinavian countries supports the hypothesis that certain environmental antigens may be triggers for the inflammation observed in sarcoidosis. These different risk factors of race, genetics, and geography appear to influence each other and further knowledge and understanding of these interactions is important to further decipher disease pathogenesis.

The diagnosis of sarcoidosis is made by a combination of laboratory tests, imaging, and clinical findings. To date it still remains a diagnosis of exclusion with no single test that can clinch the diagnosis. A tissue biopsy showing noncaseating granulomas can be highly suggestive in the appropriate clinical context. As granulomatous inflammation is not specific to sarcoidosis, alternative diagnoses (particularly infectious etiologies) should be considered and excluded. Classic sarcoid granulomas exhibit a tightly packed arrangement of macrophages, T lymphocytes, and giant epithelial cells surrounded by lamellar collagen without central necrosis. Even within the lung parenchyma, there is diversity in presentation ranging from small nodules to conglomerated masses to progressive fibrotic disease. Lung function parameters can indicate both obstructive and restrictive patterns, often in combination.

Historically, staging of sarcoidosis has been established based on chest x-ray findings as described by Karl Wurm and Guy Scadding in 1961. This convention has persisted since then, largely due to the low cost, near ubiquitous access, and simplicity in interpretation of the plain radiograph. There are, however, limitations to the Wurm-Scadding staging, including poor correlation with pulmonary function tests, lack of sensitivity for more subtle but clinically significant parenchymal disease, and lack of concordance with significant extrapulmonary disease. High resolution CT scans are more sensitive for the detection of parenchymal lung disease and correlate better with pulmonary function tests compared to plain radiographs. 

The clinical presentation of sarcoidosis can be acute and self-limiting, such as with Lofgren syndrome, the clinical triad of hilar lymphadenopathy, erythema nodosum, and arthralgias; alternatively, the course may be chronic and progressive, as with fibrotic lung disease. Disease severity and activity dictate the need for therapy: for example, isolated findings of mediastinal lymphadenopathy usually require no directed treatment, whereas inflammation in the lungs, heart, and brain can cause life-threatening organ dysfunction that warrants treatment and close monitoring. There is presently no cure for sarcoidosis, but the disease can be managed with various immunosuppressants.

The ATS and the Foundation for Sarcoidosis Research is heavily invested in research to further understand the pathogenesis of the different phenotypes of sarcoidosis, which is the basis to identify and develop novel treatment of sarcoidosis and provide better management for individual patients. While much progress has been made in the field of sarcoidosis, many questions remain unanswered: What is the stimulus for inflammation? Can we identify biomarkers or clinical variables that can predict disease progression? Is the efficacy of immunosuppressant therapy variable across populations and disease phenotypes?  In line with these questions, several studies focus on the characterization of clinical phenotypes as well as genetic profiles that will help to develop more precise treatments. In addition, an international patient survey highlights the importance of quality of life and functionality for patients with sarcoidosis and these parameters are included in clinical management and trials. Progress in basic research has been substantial and revealed that specific (T and B) lymphocytes are critical for pathogenicity and chronicity of sarcoidosis more recently, an autoimmune feature of sarcoidosis has been discussed. These promising research findings and projects need to be further supported and developed. The ATS and the Foundation for Sarcoidosis Research are committed to supporting further scientific inquiry and raising awareness to improve the lives of those affected by this complex disease.

Quick Facts About Sarcoidosis

  1. Sarcoidosis is an inflammatory disease characterized by the formation of granulomas, tiny clumps of inflammatory cells, in one or more organ of the body. When the immune system goes into overdrive and too many of these clumps form, they can interfere with an organ’s structure and function. 

  2. While the disease can affect virtually any organ in the body including the skin, lymph nodes, heart, nervous system, and joints, over 90% of cases include lung involvement (Drent M, 2013.)

  3. Disease presentation varies widely. Most patients present with symptoms between 20-40 years of age (Drent M, 2013.) In the U.S., the incidence rate in African Americans is threefold to fourfold higher compared to Caucasian patients (Baughman RP, 2001), however the disease has been characterized in all demographics regardless of age, gender or race.

  4. Sarcoidosis is classified as a rare disease, estimated to affect 200,000 Americans.