Imagine spending six years of your life dealing with constant dizziness, blurred vision and such debilitating fatigue that you are constantly visiting doctors only to be told they aren’t quite sure what’s wrong. From 1986-1992, that was Robbie L. Darden’s reality. “I was at the point where I was hesitant to tell doctors anything new,” the Indiana resident told Real Health. “I [just] knew they thought I was a hypochondriac.”

Finally in 1992, after lingering chest pains, an abnormally high pulse and a lung biopsy, a nurse suggested that Darden may have sarcoidosis, a rare immune system disorder that targets the lungs and lymph nodes, the nervous system and organs including the skin, eyes, liver, kidneys and heart. The disease causes inflammation and scarring of body tissue and can produce lesions (granulomas) in various organs. The illness can be mild and go into remission, or it can be extremely severe and even lead to death. Sarcoidosis disproportionately affects African Americans younger than 40, especially black women. While there is effective treatment, currently there is no cure.

“When I was first diagnosed, I remember being in a daze because the name itself was really scary,” Darden recalls. “All I could think is, I’m 35 years old on this hospital’s cardiac floor having all of these problems.”

But Darden was not alone. After the recent death of famous comedian Bernie Mac from pneumonia, fans learned that he suffered from sarcoidosis for years before it went into remission in 2005. “Mac’s death truly resonated with patients across the country because they felt isolated,” says Debbie Durrer, the executive director of the Foundation for Sarcoidosis Research.

The cause of sarcoidosis is unclear, yet many experts believe that genetics and environmental factors play a role. “A significant proportion of cases are related to genetics,” Marc Judson, MD, director of the Medical School of South Carolina’s Sarcoidosis Center, tells Real Health. Past studies have shown that about 19 percent of African Americans with sarcoidosis have a first-degree relative (the parents, brothers, sisters or children of an individual) affected with the disease. Doctors now believe that Darden’s 15-year-old brother, who died during a high school gym glass after complaining of dizziness, may have had sarcoidosis as well. that went undiagnosed. (Darden’s parents do not have the disease.)

The National Heart, Lung and Blood Institute estimates that tens of thousands of Americans suffer from this frequently misdiagnosed “invisible disease” that often lacks physical symptoms. But experts are finding that skin lesions—a symptom of the disease—often help them to correctly diagnose the condition. “Patients who have skin lesions are much more quickly diagnosed if a dermatologist biopsies them,” Dr. Judson says.

Once patients are successfully diagnosed, the drug treatment most often prescribed is corticosteroids. These steroid hormones reduce inflammation throughout the body thereby slowing, stopping or even preventing organ damage. But there are drawbacks: the medication does not fix tissue scarring, which can affect how organs work and many of these meds can weaken the immune system, which makes patients more susceptible to infections and other diseases. Darden can confirm this—she is dealing with increased blood sugar and pulmonary hypertension developed after starting corticosteroid treatment.

While sarcoidosis may severely affect patients physically, it may also affect them mentally—about 60 percent of sarcoidosis patients are diagnosed with depression. Encouraged by a friend, Darden and a fellow sarcoidosis patient launched the Central Indiana Sarcoidosis Support Group in 1998. “We both knew that if we felt this way—meaning there was nobody out there to talk to and no information to access—probably there were other people out there who felt the same way we did,” she says.

Darden recognizes that while her support comes from people who understand what she’s experiencing, she is also grateful for her primary care physician who urges her to ask questions about the disease. “Knowledge is power,” she says. “The more you know about something the less fear you have of it.”

Learn more about sarcoidosis at stopsarcoidosis.org.