Sarcoidosis

Sarcoidosis is a non-caseating granulomatous multi-system disease with a wide range of clinical and radiographic manifestations. 

Individual systemic manifestations are discussed in respective articles: 

The remainder of this article pertains to a general discussion of sarcoidosis. 

Sarcoidosis occurs all over the world in all ages and races. Attempts to describe an accurate epidemiology are complicated by use of inconsistent diagnostic criteria and variable (often asymptomatic) 9 disease manifestations.

Still, certain epidemiological patterns are reported in the literature:

  • age of onset
    • most commonly presents between 2nd through 4th decades of life, although diagnosis in children and elderly also recognized 3
  • gender
    • inconsistent data 6
    • there may be a small female predominance amount African-Americans 3,6
  • race
    • highest incidence in African-Americans (36 to 50 per 100,000) 5 and northern European Caucasians
    • incidence among Caucasians has been estimated at 11 to 20 per 100,000 4,5
    • reported incidence is lower in Asian populations
  • heritability
    • familial clustering of sarcoidosis has been reported, suggesting either a genetic or environmental component of the disease 3,5,7
    • the two largest studies suggest a familial relative risk increase ~4x given a single affected first-degree relative 7

Clinical presentation is variable and diagnosis is usually made on the combination of clinical and radiological features.

  • half of patients are asymptomatic
  • the rest develop respiratory (e.g. cough and dyspnoea) or skin (e.g. erythema nodosum, lupus pernio, scars, plaques) disease 3
  • ocular, lacrimal gland and salivary gland involvement are relatively common
  • approximately 5% of patients develop neurosarcoidosis 4

Additionally, patients may have specific syndromic presentations:

Sarcoidosis is a multisystem disorder of unknown aetiology characterised by the formation of inflammatory non-caseating granulomas within affected tissues. Histologically, the lesions characteristically demonstrate an absence of necrotic component, except in rare cases (so-called "necrotising sarcoid granulomatosis"). The granulomas may resolve spontaneously or progress to fibrosis.

It is thought to represent a disorder of immune regulation, particularly of cell-mediated immunity 3. Mycobacterium and propionibacterium RNA and DNA have been detected in sarcoidosis lesions, raising the possibility of an infectious trigger 4. Reported familial clustering and co-occurrence in monozygotic twins suggests that genetic susceptibility may also play an important role.

Characteristic (but not pathognomonic) histological features include:

  • non-caseating granulomas 5
    • epithelioid cells, macrophages, multi-nucleated giant cells, and CD4+ T cells
    • fibroblasts, B lymphocytes, and CD8+ T cells may be present more peripherally
  • Schaumann bodies: laminated calcium-containing concretions
  • asteroid bodies
  • necrosis is atypical, and may suggest another etiology etiology 5

Biochemical markers include:

  • elevated angiotensin-converting enzyme (ACE)
    • 40% false negative
    • 10% false positive 3
  • hypercalcaemia and hypercalciuria

Additionally, a positive Kveim-Siltzbach skin test helps confirm the diagnosis 3.

90% of patients have pulmonary involvement (although many are asymptomatic) 8. Since chest x-rays are readily available and have low radiation burden, the pattern of nodal and parenchymal involvement is typically used to 'stage' sarcoidosis (chest x-ray staging of sarcoidosis) 3.

Treatment is primarily with judicious use of corticosteroids, to avoid adverse medication effects. 

Pulmonary involvement is responsible for the majority of morbidity and mortality in patients with sarcoidosis. The overall mortality rate is approximately 5%, with patients who present insidiously faring worse than those who present with an acute onset 1,3. Likelihood of resolution depends stage of disease at presentation 3:

  • stage I: 60% resolution within 1-2 years
  • stage II: 46%
  • stage III: 12%

Complications depend on the systemic pattern of disease involvement. As pulmonary sarcoidosis is by far the most common manifestation, so are thoracic complications. They include 3:

Historically, sarcoidosis was also known as Besnier-Boeck disease, Boeck disease, or Schaumann syndrome 10

Sarcoidosis is derived from the Ancient Greek terms, σαρξ (sarc) meaning flesh, ειδος (eidos) meaning form, and σις (-sis), a suffix meaning a process 10,11.

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Article information

rID: 2019
Synonyms or Alternate Spellings:
  • Besnier-Boeck disease
  • Sarcoid (general)
  • Schaumann disease
  • Schaumann sarcoid
  • Schaumann syndrome
  • Boeck syndrome
  • Sarcoidosis (general)

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Cases and figures

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    Sarcoidosis

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    Figure 1: gross pathology - chest
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    Case 1: stage II
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    Case 2: stage IV
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    Case 3: neurosarcoidosis
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    Case 4: skull lesions
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    Case 5: skeletal manifestations
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    Case 6
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    Case 7: hand involvement
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    Case 8: mediastinal adenopathy
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    Case 9: hand involvement
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    Case 10: feet (and hand) involvement
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