Granuloma annulare

GA · localised granuloma annulare

A ring of firm papules with no scale - benign, self-limiting and treated as ringworm for months because of the annular shape.

GPBand D

Red flags

Widespread or generalised disease - worth dermatology assessment rather than reassurance alone, and a firmer prompt to screen for the associated conditions. The cited review reports the comorbidity associations for granuloma annulare as a whole and a greater quality-of-life impact when widespread; it does not grade comorbidity by extent, so no such gradient is claimed here
Ulceration, pain or rapid growth - this is not granuloma annulare and needs a different pathway
Lesions on the ear, nose or a chronically sun-exposed site in an older patient that are growing - do not assume a benign annular lesion, and refer
A patient with the eruption who has not had a recent glucose and lipid check - granuloma annulare is associated with diabetes, hyperlipidaemia and autoimmune disease, so this is a prompt for the GP rather than an ED investigation

Recognise

On light skin

Rings or arcs of small, firm, smooth papules, skin-coloured to pink or red, with a clear centre, on the backs of the hands and feet - and no scale at all.

On brown and black skin

The papules commonly appear violaceous, dark brown or simply skin-coloured rather than the erythematous ring of the textbook description, so the lesion can read as a patch of pigmentation and the raised structure is easy to miss on inspection. That colour description is clinical observation rather than a cited finding - the review cited here describes granuloma annulare as erythematous, which is itself the problem. Feel the edge: the diagnosis is a palpable rim of firm, smooth papules around a normal centre, and that is entirely tone-independent. The single most useful discriminator is also tone-independent - there is no scale - though that test weakens in anyone who has already applied a topical steroid, because steroid-modified tinea loses its scale and its defined edge. Post-inflammatory hyperpigmentation persists after the lesions flatten and is frequently mistaken for continuing disease.

In any skin tone

An annular plaque with a palpably raised, beaded edge and a normal-looking centre
No scale, anywhere on the lesion - the discriminator from tinea corporis. But ask what has already been put on it: a lesion treated with a topical steroid may have lost its scale (tinea incognito), so absence of scale means much less in a steroid-exposed lesion
Not itchy, or only slightly so, and not painful - which also separates it from tinea and from eczema
Firm and smooth on palpation; the papules feel deeper than they look
Usually on the backs of the hands and feet and over joints, and often asymmetrical
Self-limiting in most people, though it may take months to years, and it recurs

Distribution

Most often the backs of the hands and feet, and over the joints of the fingers, wrists and ankles. Localised disease is the usual pattern; generalised disease is less common and has a greater impact on quality of life.

Photographs

Granuloma annulare on the dorsum of the foot. Small firm skin-coloured and dull pink papules arranged in a ring with a clear, normal centre, — Granuloma annulare on the dorsum of the foot. Small firm skin-coloured and dull pink papules arranged in a **ring with a clear, normal centre**, and - the detail that settles it - **no scale anywhere on it**. That is what separates it from ringworm, which is the diagnosis it is almost always given: tinea scales, especially at the advancing edge. It is symptomless and self-limiting, and needs explanation rather than an antifungal. The only openly licensed photograph found for this entry shows light skin. **That is a limitation of this page, not of the disease** - a darker-skin photograph is still being sought.
Fitzpatrick II (Fitzpatrick type estimated from the photograph, not stated by the source) · Mravlja Matjaz · Wikimedia Commons - Granuloma anulare 3.jpg · CC BY-SA 4.0

Provenance for every photograph in this library: image licences. How much of the corpus still has no darker-skin photograph: skin tone coverage.

Mimics

Tinea corporis, cruris and pedis — The mistake that actually happens. Both are annular with a raised edge, but tinea corporis scales at that edge and itches; granuloma annulare has no scale. Months of antifungal for granuloma annulare is a common history
Lichen planus — Annular lichen planus also gives violaceous papules, but they are flat-topped and shiny with Wickham striae and are usually itchy
Pityriasis rosea — Both give oval or annular truncal lesions; pityriasis rosea has a trailing collarette of scale and a self-limiting course over weeks
Lyme disease and erythema migrans — Erythema migrans is a single expanding ring that grows over days after a tick bite, is flat rather than beaded, and needs antibiotics urgently
Psoriasis, including guttate — Annular psoriasis has thick adherent scale and a well-demarcated flat plaque rather than a beaded papular rim

What to do in the ED

Run a finger over the edge and look for scale, then ask what has already been applied to it. A raised, beaded, scale-free rim in a steroid-naive lesion is granuloma annulare; a scaling advancing edge is tinea
Take scrapings for mycology unless the lesion is classical and has had no steroid on it. A negative scrape costs nothing; a tinea missed because a steroid flattened its scale costs months. Do not commit to a long antifungal course on appearance alone either
Reassure explicitly: this is benign, not infectious, not contagious, and usually self-limiting - though it may take months to years and it can recur
Do not prescribe an antifungal for it, and stop one that has been started for it and has not worked
Ask the GP to check glucose and lipids, and to consider thyroid function - the recognised associations are diabetes mellitus, hyperlipidaemia and autoimmune disease including thyroiditis, rheumatoid arthritis and lupus
Refer to dermatology for widespread disease, diagnostic uncertainty, or where the appearance is causing significant distress - the cited review notes there are no treatments approved by the US Food and Drug Administration, and UK licensing is not stated there, so treatment is a specialist conversation
Warn about the pigment change that follows, particularly in brown and black skin, so the flattened lesion is not read as active disease

Disposition

Reassure and discharge for typical localised disease, with GP follow-up for the metabolic and autoimmune associations. Routine dermatology referral for widespread disease, diagnostic uncertainty or significant distress.

Safety-netting

This is a harmless skin condition. It is not ringworm, it is not an infection, and you cannot pass it to anyone - so antifungal creams will not help it. It usually clears by itself, but that can take many months and sometimes longer, and it may come back. See your GP for a blood sugar and cholesterol check, because this condition is sometimes associated with those. Return if the lesions become painful, break down or start growing quickly, or if they spread widely across your body. The darker marks left behind after the lumps flatten are not scars and will fade slowly.

Sources

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