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Granuloma annulare
Granuloma annulare (GA) is a common condition of unknown cause which affects the skin of children, teenagers or young adults (or any age group, less commonly).
Granuloma annulare can occur on any site of the body and is occasionally quite widespread. It only affects the skin and is considered harmless. Granuloma annulare may cause no symptoms, but affected areas are often tender when knocked.
Often granuloma annulare 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.
What does it look like?
There are several subtypes described:
Localised granuloma annulare
Skin coloured bumps occur in rings often over joints, particularly the knuckles. The centre of each ring is often a little depressed. It usually affects the fingers or the backs of both hands, but is also common on top of the foot or ankle, and over one or both elbows.
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Generalised granuloma annulare
Widespread skin coloured, pinkish or slightly mauve-coloured groups of small papules, usually arranged symmetrically in rings 10cm or more in diameter and often around the skin folds (armpits, groin). Extensive granuloma annulare is sometimes associated with diabetes mellitus.
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Deep granuloma annulare (pseudo-rheumatoid nodules)
This favours scalp margins, finger tips and shins. Nodules under the skin have a rubbery feel. They look rather like rheumatoid nodules but arise in people that do not suffer from rheumatoid arthritis.
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More images of granuloma annulare ...
How is the diagnosis made?
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.
What treatment is available for granuloma annulare?
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. Small plaques can be frozen (cryotherapy). Topical imiquimod and topical calcineurin inhibitors (tacrolimus and pimecrolimus) have been reported to help individual cases.
In very widespread cases, other treatments may be tried. None of these can be relied upon to clear granuloma annulare, and there are some potential adverse effects.
- Systemic steroids
- Isotretinoin
- Methotrexate
- Potassium iodide
- Dapsone
- Pentoxifylline
- Photochemotherapy (PUVA)
- UVA1 phototherapy (not available in New Zealand)
- Photodynamic therapy
- Ciclosporin
- Biological response mediators
Even if the treatment proves successful the granuloma annulare tends to return when it is discontinued.
Related information
On DermNet NZ:
Other websites:
- Granuloma Annulare – emedicine dermatology, the online textbook
Books about skin diseases:
See the DermNet NZ bookstore