When was sarcoidosis discovered?

There has been an awareness of sarcoidosis for more than 100 years since it was first described by a London surgeon-dermatologist, Dr. Jonathan Hutchinson in 1877. The doctor described the findings of a 50 year-old man who had large purple skin plaques on the hands and feet and a 64-year-old woman with large purple patches on her face and arms.

In 1889, a Norwegian dermatologist Dr. Cesar Boeck named the process "multiple benign sarcoid of the skin". He also showed that many patients also had sarcoid in the lymph nodes and lungs.

In 1958, scientists from all over the world met at the Brompton Hospital in London for a conference about sarcoidosis. Since then there has been a yearly international sarcoidosis conference. There is a scientific journal for sarcoidosis. The search for the cause and the search for new treatments continue at an intense pace.

What causes sarcoidosis?

The cause of sarcoidosis is not known; however, this diagnosis is what is known as a "diagnosis of exclusion". This term is used for a disease that has no known cause, but mimics other disorders that must first be excluded before establishing the diagnosis of sarcoidosis.

For example, there is a lung disease called hypersensitivity pneumonia (HP), which is also referred to as allergic alveolitis that must be excluded. This is an acute or chronic granulomatous lung disorder that is caused by an immune response to a variety of organic substances (antigens) that include bird proteins, spores of microbes, or airborne bacteria. There are over 300 agents that have been reported to cause this disorder. Hypersensitivity pneumonia may occur as a reaction to protein material from pigeons (pigeon breeder’s disease) or parakeets, from contaminated humidifiers or air conditions in the home, office or automobile (humidifier lung), or from mists created from contaminated water such as a basement shower or sauna.

Hypersensitivity pneumonia may have the same symptoms and identical chest x-ray findings as sarcoidosis. A blood serology test that is positive for the causative agent can diagnose hypersensitivity pneumonia. Avoidance of the causative agent can result in resolution of the illness. Sometimes, a brief course of corticosteroid treatment is utilized in the acute form of hypersensitivity and a longer course for the chronic form.

Chronic fungal infections of the lung such as histoplasmosis can also mimic sarcoid in certain situations, and these disorders must also be excluded. The fungal disorders are treated with a long course of specific types of antibiotics.

Exposures to certain metal dusts can cause a disorder indistinguishable from sarcoidosis. In the late 1940’s there was a group of patients with "sarcoid" in the region of Salem, Massachusetts. It was even called "Salem Sarcoid". Dr. Harriet Hardy investigated the disorder and discovered that it occurred only in employees working in a factory where the metal, beryllium, was used to increase the duration of use of fluorescent light bulbs. This disorder was called berylliosis. The use of beryllium in fluorescent lights was stopped after the description of the disorder and no more cases of "Salem Sarcoid" occurred. Avoiding exposure to beryllium can result in resolution of the acute form of the illness, although, a course of corticosteroid treatment is generally utilized. The chronic form is more difficult to treat.

Does sarcoidosis occur outside of the lung?

Sarcoidosis occurs in the lung or the lung-related lymph nodes in 90% of patients. In some of these patients, there may also be sarcoidosis in one or more other locations such as the lymph nodes, skin, liver, heart, kidneys or the nervous system. Sarcoidosis without involvement of the lung occurs in less than 10% of patients.

Specifically, sarcoidosis occurs in the lymph nodes in the hilar regions of the lungs in 75% to 90% of patients and in the lungs themselves in 50% of patients. Sarcoidosis involves the lymph nodes elsewhere in the body in 30% of patients, the eyes in 20%, the skin in 20%, the heart in 10%, the bones in 10% and the neurological system in less than 5 percent of patients.

In 10% of patients, the calcium level in the blood may be increased. In rare situations, the level of calcium may be so high that treatment will be required to decrease the level before an adverse reaction develops.

How do you get sarcoidosis?

No one knows. Sarcoidosis is not contagious. In rare situations, it has been reported to occur in twins and family members, but a consistent inheritance pattern has not been established.

One theory of the mechanism of disease is that an antigen exposure causes dysfunction of the lung immune response resulting in a T-lymphocyte immunity that promotes inflammation and granulomas in the lung.