Sarcoidosis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Sarcoidosis is a multisystem granulomatous disorder of unknown cause, characterised by the formation of non-caseating granulomas, most commonly affecting the lungs, lymph nodes, skin, and eyes.

Aetiology

  • Exact cause is unknown, but likely due to an abnormal immune response to environmental or infectious triggers in genetically susceptible individuals.
  • Potential triggers include mycobacteria, Propionibacterium, and occupational/environmental exposures.

Pathophysiology

  • Chronic immune activation leads to the formation of non-caseating granulomas in affected organs.
  • Granulomas consist of macrophages, lymphocytes, and multinucleated giant cells.
  • Fibrosis and scarring can develop over time, leading to organ dysfunction.

Risk factors

  • Age 20–40 years.
  • Female sex.
  • Black ethnicity (higher prevalence and severity).
  • Family history of sarcoidosis.
  • Occupational exposure to inorganic dusts or bioaerosols.

Signs and symptoms

General Symptoms:

  • Fatigue.
  • Weight loss.
  • Fever.
  • Night sweats.

Pulmonary Involvement (Most Common):

  • Persistent dry cough.
  • Dyspnoea (shortness of breath).
  • Chest pain.
  • Bilateral hilar lymphadenopathy on chest X-ray.

Extrapulmonary Manifestations:

Skin:
  • Erythema nodosum: Painful red nodules on shins.
  • Lupus pernio: violaceous plaques on the nose and cheeks.
Eyes:
  • Uveitis: red, painful eye with photophobia.
Cardiac:
  • Arrhythmias or heart block.
  • Cardiomyopathy (rare but serious).
Neurological:
  • Facial nerve palsy.
  • Neurosarcoidosis (seizures, meningitis like symptoms).

Investigations

  • Blood tests:
    • Raised serum angiotensin-converting enzyme (ACE) (not diagnostic).
    • Hypercalcaemia due to increased vitamin D activation.
    • Full blood count (to check for anaemia).
  • CXR: bilateral hilar lymphadenopathy (stage 1 sarcoidosis).
  • High-resolution CT (HRCT) chest: reticulonodular changes, interstitial lung disease.
  • Spirometry: restrictive pattern (↓ FVC, normal or ↑ FEV1/FVC ratio).
  • Bronchoalveolar lavage: increased lymphocytes in pulmonary sarcoidosis.
  • Tissue biopsy: non-caseating granulomas confirm the diagnosis.

Management

1. Observation:

  • Many cases are self-limiting and do not require treatment.
  • Regular monitoring with lung function tests and imaging.

2. Pharmacological Management:

  • Oral corticosteroids: first-line treatment for symptomatic disease (prednisolone 20–40 mg daily, tapered over months).
  • Immunosuppressants: methotrexate or azathioprine if steroid-sparing therapy is needed.
  • Anti-TNF agents: considered in refractory cases.

3. Supportive Management:

  • Calcium and vitamin D monitoring (hypercalcaemia risk).
  • Ophthalmology review if uveitis suspected.
  • Cardiac monitoring in suspected cardiac sarcoidosis.
NeurologymypanotesSarcoidosis