Granuloma annulare (GA) is a common condition of unknown cause which affects the skin of teenagers or young adults (or any age group, less commonly).

In granuloma annulare, skin coloured bumps occur in rings often over joints, particularly the knuckles. The center of each ring is often a little depressed. It usually affects both hands, or limbs, symmetrically. It can occur on other sites of the body such as the abdomen or neck, and is occasionally quite widespread. A few patients with extensive granuloma annulare have diabetes mellitus.

Granuloma annulare may cause no symptoms, but it is usually tender when knocked. Often it will disappear after a few weeks or months without leaving a scar, but it may recur at the same site or somewhere else at a later date.

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.

In most cases no treatment is required because the patches disappear by themselves in a few months leaving no trace. However, sometimes they persist for years. Sometimes it is helpful to apply a strong steroid preparation to the skin or steroids can be injected into the bumps themselves.

In very widespread cases, some certain oral treatments or Photochemotherapy (PUVA) may be tried. Although often successful the granuloma annulare tends to return when they are discontinued.