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Sarcoidosis is an inflammatory, multisystemic disease of unknown cause with a wide range of clinical manifestations. It can affect virtually any organ in the body, but predominantly affects the lungs, lymphatic system, skin, eyes, or a combination of these sites. The hallmark sign of sarcoidosis is the formation of granulomas which, if in the lungs, can be seen on X rays. A granuloma is a small area of inflammation which is usually noncancerous. They seem to be a defensive mechanism that triggers the body to “wall off” foreign invaders such as bacteria, fungi, or foreign bodies to keep them from spreading. The first description of sarcoidosis dates back to 1880s London. Despite the work of several generations of researchers, our understanding of the disease mechanisms and causes of sarcoidosis remains limited. It is currently thought that the disease stems from a dysregulated immune system response against certain environmental antigens that results in sustained granulomatous inflammation and failure to clear the offending antigens.

The prevalence and presentations of sarcoidosis are variable. The triggering antigen is thought to vary depending on race or ethnic group, geographic location, and individual genetic background. Also, the prognosis is highly variable ranging from spontaneous resolution to chronic inflammation and organ failure. Sarcoidosis occurs throughout the world and affects all races and ethnic groups, with a slight predominance among women. While it can occur at any age, it is mostly seen in men aged 30 to 50 and women aged 50 to 60. There is a definite genetic component, for example having a first-degree relative with the disease raises a person’s risk of getting it by a factor of 3.7. Getting sarcoidosis requires both a genetic predisposition and exposure to unknown substances or microbial antigens. These environmental factors include exposure to moldy environments, occupational exposure to insecticides, agricultural employment, metalworking, firefighting, exposure to inorganic dust and silica dust, and handling of building supplies (as indicated by cases of sarcoidosis in rescue workers at the World Trade Center).

As mentioned above, the histologic (pathologic) hallmark of sarcoidosis – granulomatous inflammation – is thought to be a dysregulated immune system response to unknown environmental exposures in a genetically susceptible individual. While sarcoidosis has widely variable symptoms, the most common presenting symptoms include cough, shortness of breath, chest pain, and pronounced fatigue. Although most patients with sarcoidosis are asymptomatic or have acute symptoms with spontaneous resolution, approximately one third of patients have waxing and waning or relentlessly progressing symptoms over time. The management of sarcoidosis is a major clinical challenge because of the highly variable disease manifestations. The decision of whether (and, if so, when) to treat depends on two major factors: the risk of organ failure or death and the extent to which the patient’s quality of life is impaired. Because sarcoidosis is an inflammatory disease, the goal of treatment is to blunt the body’s immune system response. The most effective medication available to suppress the immune system is glucocorticoids (steroids, e.g., prednisone). Unfortunately, steroids have dose-dependent serious side effects that tend to accumulate with prolonged use. Often, extended treatment must be given using second-line, non-steroidal medications. An alternative in this category includes the antimalarial agent hydroxychloroquine, lately of COVID-19 fame.

Meanwhile, the search for specific environmental triggers and genetic factors goes on, as does research into treating sarcoidosis. In this day of modern medical marvels, it is hard to fathom how we have a disease like sarcoidosis that remains so mysterious and poorly understood.

By Peter Galvin, MD

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