What is Sarcoidosis?
Sarcoidosis is an inflammatory disease characterized by the formation of tiny clusters of immune cells called granulomas. These granulomas can develop in various organs, most commonly the lungs and lymph nodes, but also in the skin, eyes, heart, and other organs. The condition varies widely in severity, ranging from mild, self-limiting disease to chronic, progressive illness.
Causes and Risk Factors
The exact cause of Sarcoidosis remains unknown. Researchers believe it results from an abnormal immune response to an unknown trigger, possibly involving infections, environmental factors, or genetic predisposition. It tends to affect adults between the ages of 20 and 40 and may be more common in certain ethnic groups.
Pathophysiology
It is due to an exaggerated response of immune system to an unknown agent that results into accumulation of inflammatory cells resulting into non-caseating granuloma formation. This immune process involves activation of CD4+ T cells, macrophage aggregation, and high production of cytokines. If unresolved, leads to permanent tissue damage and fibrosis.
Symptoms of sarcoidosis
Symptoms of sarcoidosis depend on the organs involved and may include:
- Persistent dry cough
- Shortness of breath
- Chest pain
- Fatigue and weakness
- Fever and night sweats
- Skin rashes or lesions
- Eye irritation or blurred vision
In some cases, patients may have no symptoms, and the disease is discovered incidentally through imaging studies.
Diagnosis of Sarcoidosis
A physician may ask for various investigations to correlate with the patient’s signs and symptoms.
- CBC (lymphopenia)
- Serum Calcium level (raised Serum calcium level)
- Serum angiotensin converting enzyme level
- Chest X-ray (Bilateral hillar lymphadenopathy, used for staging the disease)
- HRCT (reticuloendothelial infiltration)
- Pulmonary Function Tests (Restrictive pattern)
- Bronchoscopy (cobblestone appearance)
- Biopsy (granulomas formation, definitive test for diagnosis)
- FDG-PET scan (detect extra-pulmonary disease)
Although biopsy is a definitive test for diagnosis, erythema nodosum with bilateral hilar lymphadenopathy is also sufficient for confident diagnosis. Clinical and HRCT findings are also useful.
Treatment of Sarcoidosis
Treatment of sarcoidosis depends on disease severity and organ involvement. Many cases resolve without therapy. When treatment is needed, options include:
- Patients present with acute illness and erythema nodosum should get NSAIDs and a short course of corticosteroids. The majority of patients receive spontaneous remission. If there is no sign of organ damage then corticosteroids can be withheld for at least six months.
- If hypercalcaemia, pulmonary impairment, renal impairment or uveitis present, then immediately start prednisolone 20-40mg per day. Topical steroids can be used for uveitis and pulmonary disease for short duration.
- In case of unresponsive patients for more than six months, immunosuppressive agents such as methotrexate 10-20mg weekly, azathioprine 50-150mg per day, and tumor necrosis factor alpha can also be used. Chloroquine, hydroxychloroquine and low dose of thalidomide are also advised in cutaneous sarcoidosis.
- Organ-specific treatments is the definitive treatment in end organ damage disease.
Prognosis
The outlook for sarcoidosis varies. The overall mortality is round about 1-5%. Many patients recover fully within a few years, especially those with mild disease. However, some develop chronic sarcoidosis, which can lead to organ damage, particularly in the lungs. Early diagnosis and appropriate management improve outcomes.
Conclusion
Sarcoidosis is a complex, multi-system disease with unpredictable progression. While many individuals experience spontaneous recovery, others may require long-term management.