What is granuloma annulare?
Granuloma annulare is a fairly common, benign skin condition that occurs mainly in young adulthood. The cause is unknown.
What does it look like?
It is characterised by red, slightly thickened-feeling rings on the skin. The centre of the patch looks like normal skin. The patches occur preferentially on the extensor side of joints, especially the knuckles of the hands, the backs of the hands, the wrist, the elbows and the knees, though other locations can also be affected. Sometimes there are only a few patches, but it can also occur very extensively over the skin. The patches cause little pain or itch.
Investigation
In most cases further investigation of the diagnosis is not necessary. Sometimes making the diagnosis by eye is more difficult, and it may be necessary to take a skin biopsy for examination by the pathologist. Because a small proportion of people with granuloma annulare also have a predisposition to diabetes and thyroid problems, the doctor will usually, after making the diagnosis, also check the blood sugar level and thyroid hormones.
How is it treated?
Treatment is usually not necessary, because the lesions are often only very local, cause almost no complaints, and generally disappear by themselves within a number of months. If desired, the patches can be treated with a corticosteroid ointment or dabbed with liquid nitrogen, though these methods are in many cases not very successful. For extensive granuloma annulare, UVB or PUVA light therapy is a possible treatment.
When to see a doctor
See your GP or a dermatologist to confirm the diagnosis if you develop ring-shaped patches on the skin, especially if they are widespread, persistent or bothersome. Assessment can also check for associated conditions such as diabetes or thyroid problems, and rule out other ring-shaped skin conditions such as ringworm.