The cause of granuloma annulare is not clear, but doctors suspect it is the result of an immune system reaction. Many disorders, infections, drugs, and environmental factors have been noticed in people who have granuloma annulare, but having granuloma annulare does not mean that another disorder is present.
Granuloma annulare occurs twice as often in women as in men.
The bumps are usually red but may be slightly bluish, yellowish tan, or the color of the surrounding skin, and a person may have one bump or several. The bumps may be tender but usually cause no pain or itching. They most often form on the feet, legs, hands, or fingers of children and adults. The bumps often expand outwardly to form rings. The center of each ring may be clear or be slightly sunken and sometimes pale or light brown. In some people, the rings become widespread.
Doctors usually diagnose granuloma annulare by its appearance.
A sample of skin may be removed and examined under a microscope (called a skin biopsy) to confirm the diagnosis.
Most often, granuloma annulare heals without any treatment, so people who have no symptoms usually require no treatment. However, healing may take years.
Corticosteroid creams or corticosteroids injected into the rash may help clear it up. Alternatively, tacrolimus may be applied to the skin. Phototherapy (exposure to ultraviolet light) and cryotherapy (exposure to cold) are other treatments that may also be used.
Hydroxychloroquine, isotretinoin, dapsone, and cyclosporine are other drugs that may be effective if rings are widespread.
Other drugs that suppress the immune system, such as infliximab and adalimumab, may be used to treat granuloma annulare, but they may also trigger the disorder in some people.