Difference Between Sarcoidosis and Tuberculosis

Sarcoidosis and tuberculosis (TB) are two diseases that primarily affect the lungs but can involve multiple organ systems. Sarcoidosis is an inflammatory disease characterized by the formation of non-caseating granulomas in various organs, most commonly the lungs and lymph nodes while Tuberculosis while Tuberculosis is a chronic bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other organs. Early and appropriate intervention can significantly improve outcomes for patients with these challenging conditions.

Comparative Table

Below is the difference between Sarcoidosis and Tuberculosis in the tabular format: 

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What is Sarcoidosis?

Sarcoidosis is an inflammatory disease characterized by the formation of non-caseating granulomas in various organs, most commonly the lungs and lymph nodes. The granulomas in sarcoidosis consist of tightly clustered immune cells, including macrophages and T lymphocytes, which can disrupt the normal structure and function of the affected organs.

Causes

The exact cause of sarcoidosis remains unknown, though it is believed to result from an exaggerated immune response to an unknown antigen. Genetic predisposition and environmental factors, such as infections or exposure to certain substances, may contribute to its development. 

Symptoms

• Pulmonary symptoms: Persistent dry cough, shortness of breath, and chest pain.
• General symptoms: Fatigue, fever, weight loss, and night sweats.
• Dermatologic symptoms: Skin lesions, such as erythema nodosum(tender red nodules on the shins) or lupus pernio (purple skin lesions on the face).
• Ocular symptoms: Eye pain, redness, blurred vision, and photophobia due to uveitis.
• Cardiac symptoms: Arrhythmias, heart failure, and palpitations.
• Neurological symptoms: Cranial nerve palsies, meningitis, and seizures.

Diagnosis

Diagnosing sarcoidosis involves a combination of clinical evaluation, imaging, and tissue biopsy. Key diagnostic tools include:

• Chest X-ray and CT scan: These imaging techniques can reveal bilateral hilar lymphadenopathy (enlarged lymph nodes in the chest) and parenchymal lung involvement.
• Pulmonary function tests (PFTs): These tests assess lung function and can indicate restrictive lung disease.
• Bronchoscopy with transbronchial biopsy: This procedure allows for the collection of lung tissue samples to identify non-caseating granulomas.
• Serum angiotensin-converting enzyme (ACE) levels: Elevated ACE levels can support the diagnosis but are not specific to sarcoidosis.
• Gallium scan: This nuclear medicine test can show increased uptake in areas of inflammation.

Treatment

The treatment of sarcoidosis depends on the severity and extent of organ involvement. Many cases are mild and resolve without treatment. However, when treatment is necessary, options include:

• Corticosteroids: Prednisone is the mainstay of treatment, reducing inflammation and granuloma formation.
• Immunosuppressive agents: Medications such as methotrexate, azathioprine, and mycophenolate mofetil are used for patients who do not respond to or cannot tolerate corticosteroids.
• Antimalarials: Hydroxychloroquine is used for skin and joint manifestations.
• Biologics: TNF-alpha inhibitors, such as infliximab, are considered for refractory cases.

What is Tuberculosis?

Tuberculosis is a chronic bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other organs. According to the World Health Organization (WHO), TB remains one of the top 10 causes of death worldwide. In 2022, there were an estimated 10 million new TB cases and 1.5 million TB-related deaths. The highest burden is observed in countries like India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh, and South Africa.

Cause 

• The Causative Agent is Mycobacterium tuberculosis 
• TB is transmitted through Airborne droplets from coughs, sneezes, or talking. 
• Once inhaled, TB bacteria settle in the lungs and can enter the bloodstream, spreading to other organs. The immune system walls off the bacteria, forming granulomas. In some cases, the bacteria remain dormant, leading to latent TB, which can reactivate when the immune system is weakened.

Symptoms

• Persistent cough (lasting more than three weeks)
• hemoptysis (coughing up blood) and chest pain
•  weight loss, night sweats, fever, and fatigue.

Diagnosis

• Tuberculin skin test (TST)
•  interferon-gamma release assays (IGRAs)
• chest X-ray, sputum smear microscopy, and culture.

Treatment

• First-Line Drugs: A standard treatment regimen includes isoniazid, rifampin, ethambutol, and pyrazinamide for the first two months, followed by isoniazid and rifampin for an additional four months.

• Drug-Resistant TB: Multidrug-resistant TB (MDR-TB) requires longer treatment with second-line drugs, which can be more toxic and less effective.

• Duration: Typically 6-9 months for drug-sensitive TB; longer for MDR-TB.

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Prognosis 

• Sarcoidosis often sees spontaneous remission, particularly in acute cases, but chronic forms can lead to severe complications like pulmonary fibrosis, necessitating careful management.
• Tuberculosis generally has a good prognosis with timely diagnosis and antibiotic treatment, though challenges persist in regions with high rates of HIV co-infection and drug-resistant TB, which complicate treatment and increase mortality.