Sarcoidosis

 

• Background

  Pathophysiology

  • Non-caseating (i.e. non-necrotising) granulomatous disease.
  • Most commonly affects lung and lymph nodes, but can affect any system.

  Epidemiology

  • Prevalence: 1/5000.
  • 2 age peaks: 20s and 40s.
  • Slightly commoner in black people.

  Stages of pulmonary sarcoidosis

  Stages 1-4 (0 if no CXR findings), with progress between them in fact rare:

  1. Lymph nodes only. 50% of cases.
  2. Lymph nodes plus interstitial lung disease (ILD) manifest as granulomas in lung tissue. 25%.
  3. ILD only.
  4. Pulmonary fibrosis.

• Signs and symptoms

  • Systemic: fatigue, arthralgia.
  • Lymphadenopathy: commonly bilateral hilar, also cervical and/or submandibular.
  • Respiratory (>90%): SOB, dry cough, wheeze.
  • Skin: erythema nodosum, lupus pernio (hard purple lesions on face).
  • Uveitis: red, painful, photophobia, blurred vision.
  • Parotitis, usually bilateral. Uveoparotid fever (aka Heerfordt's syndrome) is fever, uveitis, parotitis, and facial nerve palsy.
  • Neurosarcoidosis (<10%): CN palsies, especially 7 (can be bilateral); also 2 (blurred vision), 3, 4, and 5. Also, headache, seizures, meningitis, neuropathy.
  • Cardiac (5%): heart block, dilated cardiomyopathy.

• DDx: Bilateral hilar lymphadenopathy

  Granulomatous disease:

  • Sarcoidosis
  • TB

  Cancer:

  • Lymphoma, though extra-thoracic lymph nodes are more common.
  • Non-small cell lung cancer.
  • Breast cancer.

  Interstitial lung disease:

  • Pneumoconiosis: silicosis, berylliosis.
  • Hypersensitivity pneumonitis.

• Investigations

  Bedside:

  • ECG: may show conduction defects.

  Bloods:

  • FBC: ↓WBC (50%), ↓Hb (20%).
  • ↑ESR
  • ↑Ca2+ due to calcitriol production by macrophages.
  • ↑ACE: 50% sensitivity, so utility is questionable.
  • U+E and LFT: may be raised if there is kidney or liver involvement.

  CXR and CT chest:

  • Bilateral hilar or paratracheal lymphadenopathy.
  • Upper lobe infiltrates.
  • Beading along fissures (HRCT).

  Lung function tests:

  • Typically restrictive, but may be obstructive or mixed pattern.
  • Used for disease monitoring.

  Biopsy usually required to confirm diagnosis:

  • Flexible bronchoscopy with bronchoalveolar lavage (↑lymphocytes, ↑CD4/CD8) and biopsy.
  • Alternatives: transthoracic fine needle aspiration, lymph node biopsy via EBUS or mediastinoscopy, skin biopsy (but not of erythema nodosum).

• Management

  Asymptomatic stage 0-1 disease does not require treatment.

  Otherwise, consider steroids:

  • Systemic steroids for symptomatic lung disease. IV if acutely unwell.
  • Minimize dose, and avoid using >2 years.
  • Topical steroids for mild skin disease. Eye drops or intraocular injections for uveitis.
  • Bisphosphonates for osteoporosis protection. Avoid Ca2+ due to ↑Ca2+ risk.

  Lung transplantation can be considered in severe pulmonary fibrosis.

• Complications and prognosis

  • Most in stage 1-2 go into spontaneous remission within 2 years.
  • Of the remainder, around half are steroid responsive.
  • <5% mortality.
  • Poor prognostic features: black, chronic lung disease, lupus pernio, chronic ↑Ca2+.