Sarcoidosis is a complex multi-system inflammatory disease characterized by the formation of non-caseating granulomas (clusters of inflammatory cells) in affected organs. It commonly affects the lungs and lymphatic system but can also impact the skin, eyes, liver, heart, and other organs. Here’s an overview tailored for evidence-based biological science (EBBS) students, focusing on the pathophysiology, clinical presentation, diagnosis, and treatment of sarcoidosis.
Pathophysiology
- Granuloma Formation: The hallmark of sarcoidosis is the formation of granulomas. These are immune responses, typically to unknown antigens, where macrophages, T-lymphocytes, and other inflammatory cells aggregate. The center of a granuloma may contain multinucleated giant cells.
- Genetic and Environmental Factors: While the exact cause of sarcoidosis is unknown, it’s thought to involve genetic predisposition and environmental triggers such as infections, dust, or chemicals that initiate an exaggerated immune response.
Clinical Presentation
- Pulmonary Symptoms: The most common presentation involves the lungs, leading to symptoms such as a persistent dry cough, chest pain, and shortness of breath.
- Lymphatic Involvement: Enlarged lymph nodes, especially in the chest, are often detected on imaging.
- Skin and Eye Manifestations: Skin lesions and eye involvement like uveitis are frequent. Löfgren syndrome, a specific presentation of sarcoidosis, includes erythema nodosum (tender red nodules on the legs), arthritis, and bilateral hilar lymphadenopathy.
- Other Systems: Cardiac sarcoidosis can lead to arrhythmias or heart failure; neurological involvement might result in facial nerve palsy or other neuropathies.
Diagnosis
- Clinical Evaluation: Diagnosis involves a combination of clinical assessment, imaging, and exclusion of other diseases with similar features.
- Chest X-ray and CT Scan: These imaging tests can show the pattern and extent of lung involvement and lymph node enlargement.
- Biopsy: Confirmatory diagnosis is often obtained via biopsy, showing non-caseating granulomas.
- Additional Tests: Pulmonary function tests, blood calcium levels (hypercalcemia is common), and angiotensin-converting enzyme (ACE) levels, which can be elevated.
Treatment
- Observation: Some cases of sarcoidosis resolve without treatment, so observation is sometimes recommended.
- Corticosteroids: These are the mainstay of treatment for patients with significant symptoms or organ involvement, reducing inflammation and granuloma formation.
- Immunosuppressive Medications: For cases resistant to steroids or where steroids are contraindicated, medications like methotrexate or infliximab might be used.
- Monitoring and Supportive Care: Regular monitoring of lung function, renal function, and other involved systems is crucial, along with supportive treatments for specific symptoms, such as topical therapy for skin lesions or ocular drops for uveitis.
Prognosis
- Variable Outcome: The course of sarcoidosis is highly variable. Some individuals experience a mild illness that resolves spontaneously, while others may have chronic progressive disease that leads to organ damage and functional impairment.