Sarcoidosis
What is it?
Sarcoidosis most commonly affects the lungs but can also affect the skin and other organs. It is characterised by the formation of “granulomas” in affected areas. These are organised collections of histiocytes (a special type of inflammatory cell).
This condition tends to affect females more than males and is most common between the ages of 20 to 40. It affects people of African descent more frequently than Caucasians.
What causes it?
The underlying cause of sarcoidosis is unknown. The body’s immune system responds abnormally to an unknown trigger and leads to inflammation and granuloma formation.
What does it look like?
There are different manifestations of sarcoidosis in the skin and each type has its own distinctive appearance.
- The most common form of skin sarcoidosis appears as groups of small reddish-brown lumps. These lumps tend to be firm to touch but are not scaly. The lumps are most often seen on the face, trunk and extremities. It tends to involve scars and tattoos.
- Lupus pernio is a distressing, cosmetically disfiguring form of skin sarcoidosis. It is characterised by purplish raised skin/lumps on the nose, cheeks, ears, fingers and/or toes. Despite its name, it has no relation to lupus erythematosus which is an autoimmune connective tissue disease.
- Erythema nodosum is a temporary reaction characterised by tender red raised areas usually on the shins, which later fade to form bruise-like areas. This is a non-specific sign – there are many other possible causes in addition to sarcoidosis.
What other problems can occur with this condition?
This condition can affect any organ of the body. The skin is involved in about one third of cases. The skin symptoms may be the first obvious sign of the condition and can lead to the diagnosis of sarcoidosis in other organs.
Common symptoms of multi-organ sarcoidosis are tiredness and weight loss. The condition often affects the lungs, and can cause a persistent dry cough, wheezing and shortness of breath. Changes including enlarged lymph glands and scarring may be seen on chest x-ray. All other body systems can be affected including the eyes, nervous system, liver, heart and kidneys. Sarcoidosis can also result in raised blood and urinary calcium levels, which can increase the risk of kidney stones.
How is it diagnosed?
As there is no definitive diagnostic test, it is important to exclude other conditions that may mimic sarcoidosis. Cutaneous sarcoidosis can be suspected from the appearance of the skin but a skin biopsy is often taken to support the diagnosis and exclude other conditions.
Even though sarcoidosis may affect the skin alone, blood tests are usually taken to support the diagnosis (e.g. blood ACE levels) and assess the possibility of other organ involvement (e.g. liver function tests and blood calcium levels). As the lungs are commonly affected, lung function tests and a chest x-ray/CT scan are usually performed. Other physicians may be involved in the treatment depending on the organs affected (e.g. a chest physician may be involved to assess for lung involvement).
How is it treated?
Cutaneous sarcoidosis (sarcoidosis that affects the skin) may resolve on its own without treatment. However, the majority of people will need some form of treatment.
- Topical/intralesional treatments
Steroid creams and steroids injected directly into the affected skin areas can be effective.
- Oral treatments
Steroid tablets are commonly prescribed, especially in more severe disease. The doses for sarcoidosis affecting the skin are generally lower than for other forms of the condition.Other medications may reduce the continued need for high doses of oral steroids. These include hydroxychloroquine, doxycycline, methotrexate and newer biologic medications (eg. anti-TNF injections).
- Physical treatments
Lasers such as pulsed dye laser can be useful in the treatment of lupus pernio.
What is the likely outcome of this condition?
The likely outcome of this condition is difficult to predict. It may disappear spontaneously or require treatment over many years.
This information has been written by Dr Charlotte Thomas & A/Prof Pablo Fernández Peñas.
Updated 27 February 2017