Sarcoidosis is an uncommon autoimmune disorder of unknown cause. The disease is characterised by the presence of non-caseating granulomas which can appear almost anywhere in the body but usually appear in either the lungs or the lymph nodes. It can occasionally appear suddenly but more often than not appears gradually. Sarcoidosis can sometimes have the appearance of tuberculosis.

Epidemiology

Sarcoidosis is more commonly seen in blacks than whites, primarily people of northern European descent in the latter case. Pulmonary involvement is the most common presentation of sarcoidosis.

Signs and symptoms

Sarcoidosis is most often manifested as a restrictive disease of the lungs, causing a decrease in lung volume and decreased compliance (the ability to stretch). The vital capacity (full breath in, to full breath out) is decreased, and most of this air can be blown out in the first second. This means the FEV₁/FVC ratio is increased from the normal of about 80%, to 90%.

However, it can have systemic effects, such as skin lesions (including erythema nodosum and lupus pernio), renal, liver and heart involvement, central diabetes insipidus, and neuropathy (damage to the nerves or brain, in particular damage to the peripheral nerves causing numbness). It may also cause uveitis and retinal inflammation, which incurs loss of visual acuity.

Causes

No direct cause of sarcoidosis has been identified, although it has been variously connected with exposure to environmental toxins, environmental mycobacteria, and herpes zoster, among many possible factors. It is also thought that there may be a hereditary factor.

Treatment

Treatment is generally with corticosteroids, most commonly prednisone, although the use of corticosteroids in mild disease has been the subject of mounting doubt. Severe disease is treated with steroids, and later with steroid-sparing agents. As the granuloma are caused by collections of immune system cells, particularly T cells, there has been some indications of success using immunosuppressants, interleukin 2 inhibitors, anti-tumor necrosis factor, and some monoclonal antibody therapies. Unfortunately, there are no conclusive results.