Granuloma annulare is a long-term (chronic) skin disease consisting of a rash with reddish bumps arranged in a circle or ring. Granuloma annulare is a chronic degenerative skin disorder. The most common form is localized granuloma annulare, which is characterized by the presence of small, firm red or yellow colored bumps (nodules or papules) that appear arranged in a ring on the skin. In most cases, the sizes of the lesions range from one to five centimeters. The most commonly affected sites include the feet, hands, and fingers. In addition to the localized form, there are four less common
forms: generalized or disseminated, linear, perforating, and subcutaneous. The lesions associated with granuloma annulare usually disappear without treatment (spontaneous remission). However, the lesions often reappear. The exact cause of granuloma annulare is unknown.
In most cases, granuloma annulare causes no symptoms, or a just mild itch at the start of any new area. It can be tender if knocked. In most patients, patches occur on only one or two sites of the body, often on bony areas such as the backs of the hand, elbows or ankles. Each patch consists of tiny bumps arranged in a ring. Typically, the rings slowly grow to 1 or 2 inches across but become flatter and rather more purple in colour as they do so, and then gradually fade. Patients can develop a more widespread rash, but this is rare. In most people with this disorder, granuloma annulare will go away in about 2 years, but this cannot be predicted accurately on an individual basis.
The cause is unknown, but granuloma annulare does not damage the general health, and is not infectious or due to allergies. Some types of granuloma annulare have been linked with diabetes but this is very uncommon in the ordinary type. It usually affects children and young adults.
Most often granuloma annulare is recognised because of its characteristic apppearance. But sometimes the diagnosis is not obvious, and other conditions may be considered. In such cases, a small biopsy (when a tiny piece of skin is removed under local anaesthetic) will help to establish the cause of the rash. The biopsy shows characteristic necrobiotic degeneration of dermal collagen surrounded by an inflammatory reaction. The diagnosis of granuloma annulare is usually based on the appearance of the skin lesions. In some instances, especially in the less common types, a skin biopsy helps to prove the clinical diagnosis, A urine test for sugar is often performed too, as there is a slightly increased risk of diabetes for those with the less common, widespread type of granuloma annulare.
Treatment may improve the appearance of the rash. Treatment may include prescription steroid creams or ointments. Troublesome patches may improve using steroid creams or ointments, or occasionally steroid injections into the rings, but this is not always the case and such treatment is not recommended in every individual, as there is some risk of thinning the skin. In severe cases, your doctor may recommend other treatments. So far, no treatment has proved uniformly successful. If you have itching from the rash, a moisturizing lotion or cream, such as Vanicream or Sarna, may help.