Diverse with peak incidence in the third decade. There is variation with race and latitude. One of the causes of hilar lymphadenopathy and hypercalcaemia. It is rarely possible to be sure of the diagnosis on clinical grounds without histological evidence, unless a patient presents with Löfgren's syndrome. About 5% get sarcoid of the nervous system (neurosarcoidosis).
Respiratory symptoms present in about 90% of cases.
- Wheeze or fine anterior crackles sometimes
- Sometimes normal chest on examination
- Clubbing is rare
- Fatigue and malaise is actually very common (two thirds)
- Uveitis - important as posterior uveitis easy to miss without slit lamp examination and present in over 10%
Rare but serious.
- Isolated nerve palsy
Important as always in differential of:
- Renal stones
Important as potentially life threatening
- Arthralgia in less than 1%
- Common variable immunodeficiency
- Secondary disease especially when steroids used in treatment:
- Immunoglobulins - mainly to exclude common variable immunodeficiency - in sarcoid will have activated immune response
- Serum ACE is nonspecific and not useful in monitoring disease activity and interpretation is now understood to be modified by polymorphisms. Accordingly it is deprecated
- Chest X-ray
- Urine cells & protein
- Spirometry if chest symptoms
- ECG for arrhythmia or conduction abnormalities
- Slit lamp in proven patients to exclude posterior uveitis
- Biopsy is almost always the only way to define the diagnosis. (Gold standard).
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