Overview of Sarcoidosis

Sarcoidosis is an inflammatory disease that produces lumps of cells (called granulomas) within various organs and tissues throughout the body, most commonly the lungs.

Interestingly, many people with sarcoidosis have no symptoms, so the disease may be discovered incidentally during a routine physical exam or chest X-ray. If symptoms are present, they are usually constitutional (e.g., fever or weight loss) or related to the lung (e.g., shortness of breath or cough).

While the precise cause behind sarcoidosis is unknown, researchers suspect that sarcoidosis develops when the immune system of a genetically susceptible person responds to something in the environment.

Unfortunately, the diagnosis of sarcoidosis cannot be made with a single test. Instead, multiple tests, in addition to a medical history and physical examination, are required.

One upside, though, is that treatment of sarcoidosis is generally only needed if symptoms are bothersome, or if the disease is progressing or affecting certain organs.

Sarcoidosis is a rather unique disease because not everyone has symptoms. In fact, the disease is sometimes discovered incidentally when a person has a chest X-ray for something else.

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 (called bilateral hilar lymphadenopathy)
• Pulmonary (lung) infiltrates

If a person with sarcoidosis does experience symptoms, they usually are related to the lungs, such as shortness of breath, dry cough, wheezing, or chest discomfort. Constitutional symptoms—fever, fatigue, weight loss, and malaise—may also occur.

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

Here are some potential symptoms/signs related to these organs:

• 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 and 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 sarcoid, including different kinds of nephritis.

Twenty-five percent of people with sarcoid get some kind of eye involvement, inculding 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 potentially triggering 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 bacteria that causes tuberculosis) and Propionibacterium acnes (a bacteria found on your 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.

The diagnosis of 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 of affected tissue (called a biopsy)
• Diagnostic studies that rule out potential diseases that mimic sarcoidosis

The purpose of the medical history and physical exam is to assess for potential symptoms and signs of sarcoidosis, and to sort out whether alternative diagnoses need to be considered.

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
• 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 will be examined under a microscope for the characteristic finding of sarcoidosis, called 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 (Wegener granulomatosis)

Many people with sarcoidosis do not require treatment because the granulomas resolve over time on their own or the disease does not progress further.

For some people, though, treatment is warranted—as their symptoms impair their 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 the potential side effects it may cause, including:

• Weight gain
• Osteoporosis
• Diabetes mellitus
• High blood pressure
• Gastritis
• Myopathy
• 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., rheumatologist or pulmonologist) who have experience working with patients with this inflammatory condition.