What Is Sarcoidosis?

Sarcoidosis is an inflammatory disease that produces lumps of cells (granulomas) within various organs and tissues throughout the body—most commonly the lungs. While the precise cause is unknown, researchers suspect that sarcoidosis develops when the immune system of a genetically susceptible person responds to something in the environment. Many people with sarcoidosis have no symptoms, so the disease may be discovered during a medical evaluation of another concern.

The fact that not everyone with sarcoidosis experiences symptoms makes it a rather unique disease. If symptoms are present, they are usually constitutional or related to the lung.

Constitutional symptoms of sarcoidosis can include:

• Fever
• Fatigue
• Weight loss
• Malaise

Lung-related symptoms of sarcoidosis can include:

• Shortness of breath
• Dry cough
• Wheezing
• Chest discomfort

Sarcoidosis may affect various other organs and tissues, including the muscles, joints, eyes, skin, nerves, lymph nodes, liver, and spleen.

Some potential symptoms/signs include:

• Muscle and joint: Muscle weakness/aches and joint pain/swelling
• Eye: Dry, itchy, and/or burning eyes, blurred vision, or sensitivity to light
• Skin: New rashes, like erythema nodosum (red, tender nodules on the shin) or lupus pernio (skin sores on or inside the nose, on the cheeks, ears, eyelids or fingers)
• Nerves: Facial weakness or paralysis, as well as numbness and tingling
• Lymph nodes: Enlarged lymph nodes, especially in the neck (cervical) and above the collarbone (supraclavicular)
• Liver: Right-sided abdominal discomfort and mild elevation in liver enzymes
• Spleen: Left-sided abdominal discomfort and anemia or other blood abnormalities
• Central nervous system: Encephalopathy; granulomas; meningitis

Sarcoidosis may also affect the heart and cause heart failure, abnormal heart rhythms, and even sudden death.

Kidney problems may also occur with sarcoidosis and lead to problems with calcium regulation. High calcium levels in the blood (called hypercalcemia) and urine (called hypercalciuria) can then cause kidney stones and eventually, kidney failure. There are multiple other kidney diseases seen with increased frequency with sarcoidosis, including different kinds of nephritis.

Twenty-five percent of people with sarcoidosis get some kind of eye involvement, including uveitis.

Lastly, various glands in the body may be affected by sarcoidosis, such as the pituitary gland, thyroid, and parotid gland.

The cause of sarcoidosis remains unknown, although experts suspect that both genetics and some sort of environmental exposure are likely involved.

Some environmental sources that have been evaluated as potential triggers of the development of sarcoidosis in a genetically vulnerable person are various viruses, like the herpes virus, as well as various bacteria, such as Mycobacterium (the bacterium that causes tuberculosis) and Propionibacterium acnes (a bacterium found on the skin).

Non-infectious exposures have also been examined, including organic dust, solvents, molds/mildew, pesticides, beryllium, aluminum, zirconium, and wood stoves. None of these exposures have been definitively linked and more studies are needed.

Diagnosing sarcoidosis is often challenging because there is no single blood or imaging test that can clinch the diagnosis.

Instead, the diagnosis of sarcoidosis is based on four main factors:

• A detailed medical history and complete physical exam
• Imaging and other diagnostic tests
• A sample (biopsy) of affected tissue
• Diagnostic studies that rule out potential diseases that mimic sarcoidosis

Given that sarcoidosis may not present with symptoms, the disease is sometimes discovered incidentally when a person has a physical exam or a chest X-ray for some other reason.

During the medical history, a doctor may become suspicious for sarcoidosis if a patient's main symptoms are lung-related and accompanied by constitutional symptoms, like fever.

In addition, a patient's age and race can provide a clue to the potential diagnosis. More than 80% of sarcoidosis cases occur in adults between the ages of 20 and 50. Moreover, African-Americans are approximately three to four times more likely to develop sarcoidosis than whites.

When it comes to the physical exam, signs of sarcoidosis are often subtle or nonspecific, such as wheezing heard in the lungs.

That said, in some cases, the physical exam findings are more obvious, and if they are found in combination (for example, the eruption of an erythema nodosum rash, along with a fever and multiple joint pains), the diagnosis of sarcoidosis becomes more evident.

A variety of imaging and other tests are usually performed to help make the diagnosis of sarcoidosis.

These tests often include the following:

• Chest X-ray: The two classic findings seen on a chest X-ray of a patient with sarcoidosis are enlargement of the lymph nodes on both sides of the chest (bilateral hilar lymphadenopathy) and pulmonary (lung) infiltrates
• High resolution computed tomography (HRCT) scan of the chest
• Pulmonary function tests (PFTs)
• Electrocardiogram (ECG)
• Various blood tests: Angiotensin-converting enzyme (ACE) level, complete blood count (CBC), and comprehensive metabolic panel (CMP), to name a few
• Urinalysis and urine calcium level
• Eye exam

During a biopsy, a small sample of tissue is removed from an organ that is affected by sarcoidosis. A biopsy may be performed on the lung or other affected organ or tissue, like a lymph node, area of skin, or enlarged parotid gland. Sometimes, two different organs are biopsied to help make the diagnosis of sarcoidosis.

Once the tissue sample is removed, it is examined under a microscope for the characteristic finding of sarcoidosis—a granuloma.

Several other diseases can mimic the symptoms and signs of sarcoidosis, which is why your doctor will evaluate these alternative diagnoses:

• Infections, like tuberculosis, histoplasmosis, or human immunodeficiency virus
• Cancer, like lymphoma
• Drug-induced hypersensitivity
• Foreign body granulomatosis
• Hypersensitivity pneumonitis
• Pneumoconiosis (e.g., aluminum or beryllium)
• Vasculitis, like Churg-Strauss syndrome or granulomatosis with polyangiitis (formally called Wegener granulomatosis)

Treatment of sarcoidosis is generally only needed if symptoms are bothersome, or if the disease is progressing or affecting certain organs. For many with sarcoidosis, the granulomas resolve over time on their own or the disease does not worsen.

For others, though, treatment is warranted because symptoms impair daily functioning, their disease continues to worsen over time, and/or certain organs are affected (e.g., eyes, heart, or kidney).

A corticosteroid—most commonly prednisone—is the mainstay of treatment for sarcoidosis.

While an effective anti-inflammatory drug, the downside of prednisone therapy is its potential side effects, including weight gain, osteoporosis, diabetes mellitus, high blood pressure, gastritis, myopathy, and infection.

If a person cannot take a corticosteroid and/or their symptoms do not improve enough with a corticosteroid alone, other medications—such as one of the drugs below—may be recommended:

• Rheumatrex (methotrexate)
• Imuran (azathioprine)
• Arava (leflunomide)
• Plaquenil (hydroxychloroquine)
• Remicade (infliximab)
• Humira (adalimumab)

Sarcoidosis is not a black and white disease. Rather, it affects people uniquely, which in turn affects a person's individual treatment plan and prognosis. If you or a loved one has sarcoidosis, be sure to see specialists (e.g., a rheumatologist, a pulmonologist) who have experience working with patients with this inflammatory condition.