Sarcoidosis

Sarcoidosis is a rare chronic inflammatory disorder in which the immune system causes clusters of abnormal inflammatory cells (called granulomas) to form in various organs, therefore impairing normal function. Over time, this can lead to scarring in the affected organs and permanent damage. Sarcoidosis can afflict almost any organ, but the lymph nodes, lungs, skin, heart and eyes are most commonly affected. It is more common in women, usually developing between ages 20 and 40, but can occur in anyone. 

The exact cause of sarcoidosis is unknown but is likely due to an overactive immune response. It is contributed by a complex relationship between genetic and environmental factors.

• Genetic predisposition: Sarcoidosis is more common in people of African or Northern European descent. A positive family history increases the risk of sarcoidosis.
• Environmental triggers: infections, certain chemicals (e.g. insecticides) and environmental exposures may trigger or worsen disease in those who are genetically predisposed.
• Medications: certain medications can cause sarcoidosis, e.g. antibiotics (minocycline, nitrofurantoin), TNF-alpha inhibitors, interferons, immune checkpoint inhibitors, and certain medications to treat retroviral infection.

Sarcoidosis is rare and diagnosis can be challenging. There is no specific test to diagnose this condition, and symptoms may mimic other diseases such as infections and cancers. A comprehensive assessment will usually involve:

• A detailed history and physical examination
• Laboratory tests may show elevated calcium, angiotensin-converting enzyme (ACE) levels, and raised inflammatory markers (such as erythrocyte sedimentation rate and C-reactive protein). However, these tests are not always raised in patients with sarcoidosis. Other major organ function will be screened, such as blood counts, liver and kidney function tests. Urine studies may be performed.
• Imaging: A chest X-ray is usually performed to look for swollen lymph nodes and changes in the lungs. Further imaging such as CT or PET-CT scans may be done for further detailed assessment.
• Tissue biopsy: A small tissue sample may be required to provide more definitive evidence of sarcoidosis, and to exclude other conditions such as cancers and infections like tuberculosis. Examples include biopsy of the lymph nodes, skin rash, lung, nerves. Granulomas are usually seen when the biopsy sample is viewed under the microscope
• Other specialised tests may be performed depending on the suspected organ involvement e.g. MRI of the brain for suspected neurological involvement, lung function tests (blowing tests), cardiac scans, review by an eye specialist etc.

The severity of sarcoidosis varies widely, from mild and self-limiting to life-threatening if critical organs (like the heart or brain) are involved. Your treatment plan will be carefully tailored to your symptoms, preferences, and goals of care.

• Mild cases with no major organ involvement: 
o No specific treatment is required in patients with no symptoms and no organ or life-threatening concerns 
o These patients are usually monitored longitudinally

• Symptomatic cases and/or in patients with severe disease:
o Corticosteroids are fast-acting medications that effectively suppress the immune system. Doses depend on the severity of symptoms and organ involvement. In severe cases, high doses may be required initially (given as intravenous injections through the veins or oral tablets), then reduced over time. 
o Other immune suppression medications may be given to reduce the need for long-term steroids and better control the disease. Examples include methotrexate, azathioprine, mycophenolate mofetil and leflunomide.
o For life or organ-threatening disease, stronger immune suppression medications may be required. These are often given as injection medications (either infusions – given through the veins, or subcutaneous injections given under the skin in the abdomen or thighs). These include cyclophosphamide and biologics (targeted medications) such as infliximab and adalimumab.

As multiple organ systems may be affected in sarcoidosis, patients are often cared for by a multidisciplinary team of medical professionals, including a primary rheumatologist and other relevant subspecialty teams and allied health professionals. 

To prevent infections when on high doses of immune suppression medications, prophylactic antibiotics and certain vaccinations are encouraged (e.g. influenza, pneumococcal, COVID-19, respiratory syncytial virus and shingles). Other co-existing medical conditions such as osteoporosis, high cholesterol, diabetes mellitus and high blood pressure will also be addressed.

Patients with sarcoidosis are able to live active lives with the right treatment and support. Some recommended lifestyle changes include:

• Eat a balanced diet. Avoid raw and partially cooked food to reduce risks of infections, especially if you are on medications that suppress the immune system (e.g. steroids).
• Avoid smoking.
• Stay active and exercise in moderation. Ensure sufficient rest and sleep well.
• Attend regular medical check-ups to monitor your health. Participate actively in your care and ask questions during your clinic consultations.
• Take your medications as prescribed, even when you feel well, to avoid disease flares.
• Seek immediate medical attention if you suspect that the disease is flaring up.

Seek a doctor's advice. You will be referred to a specialist (rheumatologist) who can confirm the diagnosis and start you on the appropriate treatment. Once diagnosed, it is important to start treatment early and follow your rheumatologist’s advice. This condition is managed by the Division of Rheumatology and Allergy.