Sarcoidosis

Background/Epidemiology

  • Multisystem granulomatous disorder characterised by the presence of non-caseating granulomas
  • Unknown cause
    • More common with latitude (? vit D); more common in spring/summer (? infective trigger)
    • Genetic factors likely (class II HLA confers protection)
    • Smoking ?protective

Causes/Pathophysiology

  • Likely genetic susceptibility (HLA class II); also familial clustering; Geographic and seasonal component
  • Mainly a T cell process (CD4+); infiltration in the lung causes an alveolitis involving a number of inflammatory cells; granulation tissue is laid down
  • Most cases regress but some will recruit fibroblasts and cause fibrosis (permanent)

Clinical Presentation

  • Almost 50% will be asymptomatic (found on CXR)
  • Pulmonary (>90%)
    • Non-productive cough, breathless and sometimes wheeze.
    • Fine interstitial crackles may be heard in advanced disease (particularly anteriorly: upper lobes >lower lobes)
  • Systemic
    • Fatigue (66%)
      • Can be profound
    • Fever, weight loss, general malaise; arthralgia and low mood may also be present
  • Skin (24%)
    • Erythema nodosum (classic)
    • Also maculopapular lesions, hypo/hyperpigmentation, lupus pernio (chronic raised/indurated (hardened) lesions of the skin, often purple and found on the cheeks
    • NB Ask if the patient has any scars (often infiltrated with granulomatous tissue and can be easy to biopsy)
  • Lymphadenopathy (15%)
  • Ocular (12%)
    • Uveitis can be a complication of sarcoid and can be sight-threatening
    • Patients can get asymptomatic posterior uveitis and so should be screened for eye problems at diagnosis
  • Hepatic/GI (18%)
    • Classically abnormal LFTs- raised ALT (asymptomatic)
  • Others (≤5%)
    • Renal (particularly renal stones); Neurological (can be Bell’s palsy, lymphocytic meningitis, cranial nerve palsies); cardiac (sudden cardiac arrest); musculoskeletal (although arthralgia can be common, rarely bone cysts, nodules and myosits can occur).
Löfgren's syndrome is an acute illness characterised by erythema nodosum, peripheral arthropathy, uveitis, BHL, lethargy and fever; most common in young women.  It is a very good prognosis and most resolve within a year.

Investigations

  • Blood tests
    • Full blood count
      • Lymphopenia
    • U&Es
      • Raised Ca (and hypercalciuria
    • LFTs may be mildly deranged
    • Serum ACE- measures disease activity
    • PV/CRP
  • CXR (for staging)
    • Stage I
      • Bilateral hilar lymphadenopathy (usually symmetrical); paratracheal lymph nodes often enlarged
      • Often asymptomatic, but may be associated with erythema nodosum and arthralgia
      • Most cases resolve within a year
    • Stage II
      • BHL and parenchymal infiltrates
      • Cough/breathlessness
      • Majority resolve spontaneously
    • Stage III
      • Parenchymal infiltrates without BHL
      • Less likely to resolve
    • Stage IV
      • Pulmonary fibrosis (volume loss)
      • Can cause progression to ventilatory failure, pulmonary hypertension and cor pulmonale
      • Can cause other features e.g. cavitations, bullae, calcifications)
  • Pulmonary function tests
    • Restrictive lung picture
    • Reduced gas transfer
  • Urine dipstick (exclude autoimmune cause)
  • ECG- exclude potential dangerous associated arrhythmia
  • Bronchoscopy/Biopsy
    • Cobblestone appearance
    • Non-caseating granulomatous tissue on histology
  • Further imaging
    • HRCT
      • reticulonodular opacities
    • PET scanning for extrapulmonary disease/active disease
  • Tuberculin skin test (Mantoux)
    • Negative in sarcoid due to T-cell sequestration in the lungs (not very specific)
    • If positive, consider TB as an alternative diagnosis

Management

  • 60% will spontaneously regress
    • Less favourable outcome is associated with lupus pernio, chronic uveitis, chronic hypercalcaemia, nephrocalcinosis, progressive pulmonary disease, nasal mucosal disease, cystic bone lesions, neurosarcoidosis and myocardial involvement
    • Also black ethnicity and patients >40
  • Oral steroids (Prednisolone) (High dose then reduce) only for 6-24 months (little evidence for improvement)
    • ONLY in symptomatic/clinically significant (organ-involving) stage II/III disease or
      • Hypercalcaemia
      • Neurosarcoid
      • Cardiac involvement
      • Persistent ocular involvement (after topical treatment)
  • Lung transplant can be considered at end-stage disease
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