Sarcoidosis

Dr Henry Knipe and A.Prof Frank Gaillard et al.

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

Individual systemic manifestations are discussed individually: 

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

Although the age of presentation is very broad, sarcoidosis most commonly affects patients between 20 and 40 years of age.  There is a slight female predominance, particularly among African-Americans 1,3. The overall incidence among Caucasians has been estimated at 20 per 100,000 4

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

Histology and/or a positive Kveim-Siltzbach skin test helps confirm the diagnosis 3. Biochemical markers include:

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

Sarcoidosis is a multi-system disorder of unknown aetiology characterized by the presence of widespread, noncaseating granulomas, with formation occurring in all affected tissues. 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 has been detected in sarcoidosis lesions raising the possibility of an infective component 4

Histology

Characteristic (but not pathognomonic) histological features include:

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

Treatment is primarily with corticosteroids, which must, however, be used judiciously. 

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

Complications are of course organ dependent. As pulmonary sarcoidosis is by far the most common manifestation, so are thoracic complications. They include 3:

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Article information

rID: 2019
Synonyms or Alternate Spellings:
  • 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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    Sarcoidosis

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    Case 1: stage II
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    Sarcoidosis
    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 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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