Discoid and asteatotic eczema

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Discoid plaques often begin as grouped vesicles or papules and become circular, sharply bounded and itchy. Central clearing can appear, so morphology alone may not distinguish tinea. Asteatotic eczema is a diffuse xerotic process with fine red, purple or brown cracks resembling crazed paving; shins are typical but trunk and limbs can be involved.

Ask about bathing, heating, cleansers, diuretics, oedema, varicose veins, atopy and topical products. Examine feet and nails for a dermatophyte reservoir and legs for venous signs. Treatment succeeds when dryness and inflammation are addressed together and the patient has enough product for the affected area.

Discoid and asteatotic eczema care should combine visible inflammation with itch, pain, sleep, occupation and treatment burden. Agree where each product goes, how much is used and when response will be reviewed; explain urgent features separately so normal fluctuation is not confused with infection or treatment failure.

Key points

Discoid eczema forms very itchy round or oval plaques, often weepy and crusted early and dry or scaly later; it commonly mimics tinea corporis.
Asteatotic eczema produces superficial intersecting cracks on very dry skin, often shins of older adults in cold dry conditions.
On brown or black skin, active discoid plaques may appear dark brown, purple or paler and often leave persistent pigment change.
Scrape an untreated active scaly border when dermatophyte infection is plausible before escalating topical corticosteroid.
Reduce hot bathing and harsh soap, use a generous leave-on emollient and apply a site-appropriate topical corticosteroid to active plaques for a defined course.
A solitary plaque that remains indurated, ulcerated or treatment-resistant needs biopsy consideration rather than repeated empirical cream.
For Discoid and asteatotic eczema, document body sites, severity, sleep and function, recent treatment, infection features and what the patient can realistically apply each day.
In Discoid and asteatotic eczema, reassess the diagnosis when a well-used, correctly potent regimen fails rather than repeatedly intensifying treatment without examining adherence, exposure and mimics.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Dry-barrier susceptibility

Cold low-humidity weather, hot washing, harsh cleansers, age-related lipid loss and underuse of emollient predispose skin to fissuring and inflammation.

Discoid inflammatory pattern

Coin-shaped plaques arise through an incompletely understood interaction of xerosis, atopy, microbes, trauma and occasionally contact allergy.

Lower-leg contributors

Venous hypertension, oedema and reduced mobility can aggravate discoid or asteatotic change on shins and must be separated from primary venous eczema.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Asteatotic cracking
Severe loss of stratum-corneum water and lipid creates superficial polygonal fissures, allowing irritant entry and a craquelé inflammatory pattern.
2
Discoid plaque formation
Clusters of papules and vesicles merge into sharply round inflamed plaques that may weep, crust, then become dry and scaly.
3
Scratch and colonisation
Itch and rubbing disrupt the barrier further, while bacterial colonisation increases crust without necessarily proving invasive infection.
4
Pigmentary resolution
After active inflammation settles, brown, grey or lighter coin-shaped macules may persist, especially in darker skin, without scale or warmth.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Acute discoid plaque

A round cluster of papules and tiny vesicles becomes an intensely itchy, oozing or crusted coin-shaped plaque.

Chronic discoid plaque

Dry sharply demarcated circles with scale and excoriation persist on trunk or limbs and may leave residual dyspigmentation.

Asteatotic craquelé

Fine superficial polygonal fissures cross very dry skin, classically on shins, with itch and limited ooze.

Tinea-like edge

Central clearing with peripheral scale, asymmetry or foot and nail fungus increases the probability of dermatophyte infection.

Malignancy departureRed flag

A solitary enlarging indurated plaque with bleeding, ulceration or failure of adequate therapy requires prompt specialist assessment.

Red flags requiring action

Systemic illness, painful expansion, purpura, widespread detachment, unilateral ulceration, palpable tumour, treatment-resistant annular disease or major lower-leg oedema requires broader investigation.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Whole-skin, foot and nail examinationFirst step
Why
Distinguish discoid and asteatotic patterns from psoriasis, venous disease and a fungal reservoir.
Interpretation and limitations
Record active inflammation separately from residual pigment; examine lower-leg oedema and pulses before advising compression.
02
Skin scraping for microscopy and culture
Why
Test a plausible dermatophyte mimic before corticosteroid obscures it.
Interpretation and limitations
Sample the advancing untreated scaly edge; negative results depend on specimen quality and recent antifungal or steroid exposure.
03
Bacterial swab when severe or recurrent infection is suspected
Why
Identify resistant or unusual organisms when culture will alter treatment.
Interpretation and limitations
Crust alone is not an indication; swab after treatment failure or in severe disease according to NICE NG190.
04
Patch testing for recurrent product-linked disease
Why
Assess allergic contact contribution when distribution or treatment exposure suggests it.
Interpretation and limitations
Positive sensitisation requires relevance to a product actually used on the affected site.
05
Biopsy of a persistent atypical plaque
Why
Exclude malignancy, psoriasis or another inflammatory disorder.
Interpretation and limitations
Choose the active indurated area and provide duration, failed treatment, images and differential to pathology.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Tinea corporis

An expanding annular plaque with an active scaly edge and central clearing suggests dermatophyte infection; scraping should precede stronger corticosteroid.

Plaque psoriasis

Well-demarcated thicker scale, extensor distribution, scalp or nail disease and less weeping support psoriasis rather than discoid eczema.

Cutaneous malignancy

A solitary persistent, indurated, bleeding or ulcerated plaque that fails appropriate therapy requires dermatology review and often biopsy.

Venous or contact eczema

Lower-leg oedema, varicosities and haemosiderin support venous disease, while geometric or product-linked recurrence supports irritant or allergic contact dermatitis.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Dry or asteatotic diseaseRestore barrier and reduce environmental lossFirst stepCraquelé fissures occur on dry skin without infection, tumour features or major venous disease.

1Shorten hot washing, stop harsh soap and apply a rich fragrance-free leave-on emollient at least twice daily and after washing.
2Use a site-appropriate topical corticosteroid on inflamed fissured areas for a defined short course while continuing emollient beyond clearance.
3Review heating, humidity, mobility and adequate product quantity and reassess if fissures become painful, wet or widespread.

02Coin-shaped plaquesTreat eczema after checking fungal cluesMultiple itchy round plaques occur without severe infection or suspicious solitary induration.

1Examine the active edge and feet, scrape for mycology when tinea is plausible and avoid combined antifungal-steroid treatment before sampling.
2Apply emollient widely and a potent body-site corticosteroid thinly to active plaques once or twice daily within its licensed course.
3Review in two to four weeks for flattening, reduced itch and scale, separating residual pigment from continued activity.

03Atypical or infected patternInvestigate rather than intensify blindlyA plaque is solitary, ulcerated, painful, spreading, treatment-resistant or accompanied by systemic illness.

1Assess cellulitis and systemic severity, use antibiotic guidance when genuine bacterial infection is present and arrange same-day care if unwell.
2Refer an indurated or non-healing lesion for dermoscopic assessment and biopsy rather than repeating corticosteroid.
3Reconsider tinea, psoriasis, venous eczema and allergic contact dermatitis using targeted sampling or patch testing.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

A potent topical corticosteroid for discoid or significant asteatotic body-site eczema after fungal infection and untreated bacterial disease have been considered.

Betamethasone valerate 0.1% cream

Apply a thin film to active trunk or limb plaques once or twice daily for up to four weeks, reducing frequency when inflammation is controlled.

Avoid face, folds, infection, large areas and occlusion unless directed; review atrophy and systemic absorption and stop diagnostic masking when a plaque fails to respond.

A mild topical option when site or severity does not justify a potent corticosteroid, always alongside regular leave-on emollient.

Hydrocortisone 1% cream

Adults apply thinly once or twice daily for no more than seven days under the product licence on appropriately selected mild or thin-site inflammation.

Do not use on untreated infection, eyes or suspicious lesions; prolonged use and sensitising excipients can worsen diagnostic uncertainty.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Secondary bacterial infection

Increasing pain, pustules, rapidly worsening crust, cellulitis or systemic illness can complicate barrier failure and alter antibiotic decisions.

Generalisation

Discoid plaques may become numerous or provoke widespread autoeczematisation, increasing sleep loss, treatment burden and diagnostic uncertainty.

Chronic pigment change

Post-inflammatory hyperpigmentation or hypopigmentation may remain long after active eczema and affect wellbeing or lead to overtreatment.

Masked dermatophyte infection

Potent corticosteroid applied to unrecognised tinea suppresses scale while fungal spread continues beneath treatment as tinea incognito.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Photograph and measure a solitary persistent plaque with consent so non-response, enlargement or ulceration is objectively recognised.
Review whether emollient quantity and bathing changes are sufficient to prevent new asteatotic fissures after the steroid course ends.
Track active scale, elevation, ooze and itch separately from persistent darker or lighter post-inflammatory colour.
At review of Discoid and asteatotic eczema, compare itch, sleep, fissuring or ooze, affected sites, function and treatment use with the agreed baseline.
For Discoid and asteatotic eczema, record adverse effects, new contact exposures and the safety-net for pain, fever, rapidly spreading disease, eye symptoms or systemic illness.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

A ring is not always fungus

Discoid eczema can clear centrally, so edge sampling and associated foot or nail findings improve discrimination.

Craquelé records water loss

The polygonal surface pattern reflects severe xerosis and is worsened by hot washing, low humidity and inadequate emollient.

Pigment is a slow endpoint

Residual coin-shaped colour may last months and should not be treated as persistent inflammation without texture or symptoms.

One stubborn plaque is different

Multiple relapsing discs support eczema, while a single indurated non-healing lesion deserves biopsy consideration.

Lower legs need vascular context

Oedema, haemosiderin, atrophie blanche and varicosities redirect treatment toward chronic venous hypertension.

11Common pitfallsFrequent interpretation and management errors.

01
Applying potent corticosteroid to every annular plaque before taking a scraping from a plausible active fungal edge.
02
Continuing anti-inflammatory treatment solely because post-inflammatory pigment remains visible.
03
Calling a non-healing ulcerated plaque discoid eczema for months without biopsy.
04
Treating lower-leg dermatitis without examining oedema, pulses and venous signs.
05
Prescribing emollient vaguely without enough quantity or a plan to replace soap and hot washing.