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Sarcoidosis

Synonyms: M. Boeck, sarcoid

German: Sarkoidose

1 Definition

Sarcoidosis is a immune modulating disease leading to the development of granulomas. It can affect any organ, most prominently it clinically presents with pulmonary symptoms.

2 Epidemiology

The peak age group for first manifestation is 20-40 years. Especially women seem to be first affected at either a younger age (20-30 years) or later in their life (60-70 years).

The incidence is between 10-40 per 100,000. There seem to be regional and ethnical differences, incidences are higher in Scandinavian countries and in African Americans.

Surprisingly, smokers seem to be less likely to suffer from sarcoidosis.

3 Pathology

The most striking difference in pathology of sarcoidosis compared to tuberculosis is that in sarcoidosis, the granulomas lack the necrotic centre.

Macroscopically, there are a lot of variances and combinations of symptoms in individual patients:

Lymph nodes are almost always affected, especially in the hilus area of the lung. At an early stage of pulmonary sarcoidosis, hilar lymphadenopathy is an often observed state.

In more than 70% of cases, the lung (interstitium) is affected. Since lung affection is of such a paramount importance in sarcoidosis, a classification exists:

  • Type 0 - no pulmonary involvement, isolated sarcoidosis in other organs
  • Type I - bilateral hilar adenopathy
  • Type II – additionally, involvement of pulmonary parenchyma
  • Type III – pulmonary parenchyma involved, and fibrosis
  • Type IV – end-stage lung disease with severe fibrosis

In around 20%, ophthalmological problems such as uveitis, iridocyclitis, granulomatous inflammation of the Glandula lacrimalis.

Dermatological involvement presents as Erythema nodosum or Lupus pernio.

Severe central nervous system consequences can be encephalitis, facial palsy.

In the Jüngling-syndrome, bones can be affected resulting in cystic degradation in the phalanxes.

Spleen and liver present with characteristic granulomas.

Serious complications can arise if the heart is affected, leading to electrophysiological changes and rhythmic dysregulation. However, often heart involvement stays without symptoms.

Due to hypercalzaemia related to sarcoidosis in 15% of the cases, chronic kidney failure can be a result of chronic nephrolithiasis.

4 Etiology

No casuistic explanation for the pathophysiology of sarcoidosis has yet been found. However, an association with HLA-DQB1 has been observed.

An imbalance in the regulation of immune system is believed to be the cause of sarcoidosis. While T-lymphocyte function seems to be impaired, a upregulation of B-lymphocytes activity leads to increased production of immuneglobulines (resulting in hypergammaglobulinaemia in 50% of the patients). This local hyperactivity and dysregulation of immunological systems could lead to the development of granulomas.

5 Clinical presentation

5.1 acute sarcoidosis (10%)

A combination of the first four symptoms is often described as Löfgren syndrome. Another rare syndrome is Heerfordt syndrome presenting with a trio of parotitis, uveitis and facial palsy.

In 95% of the cases, acute sarcoidosis heals in full remission.

5.2 chronic sarcoidosis (90%)

Patients with chronic sarcoidosis often are symptom free for a long period in their disease. Occasionally, mild dry coughing or dyspnoe are described.

The prognosis of chronic sarcoidosis closely correlates with the radiological classification of the progress of the disease.

6 Diagnosis

Patient history, chest radiography, or CT scans can, via exclusion of differential diagnoses, lead to the diagnosis of sarcoidosis. However, there is no specific test.

Inflammatory parameters can help in defining the inflammatory status. ACE (an enzyme in pulmonary endothel) can be assessed for control of disease progress. To identify hypercalcaemia at an early stage, calcium should be controlled. Furthermore, IgG can be assessed because of the hypergammaglobulinaemia described above.

7 Therapy

So far, no casuistic therapy could be found. Supportive anti-inflammatory and analgetic treatment can be provided. In severe cases, immune-suppressive medication and, in the ultimate stage, even a lung transplantation can be considered.

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