Medical Management of Nummular Eczema
Start with moderate-to-potent topical corticosteroids applied once or twice daily as first-line therapy, combined with aggressive emollient use and soap-free cleansers, as nummular eczema typically requires higher potency steroids than other eczema subtypes due to its thick, lichenified plaques. 1, 2
First-Line Topical Corticosteroid Strategy
Apply moderate-to-potent topical corticosteroids (such as mometasone furoate or clobetasol propionate 0.05%) once or twice daily to the coin-shaped lesions, as nummular eczema lesions are often thick and lichenified, requiring higher potency preparations than mild eczema 1, 3, 2
Potent topical corticosteroids result in a large increase in treatment success (70% versus 39% with mild potency), making them appropriate for the thick plaques characteristic of nummular eczema 2
Once daily application is as effective as twice daily for potent topical corticosteroids, so you can simplify the regimen to improve adherence 2
Use the least potent preparation that controls the disease, and implement "steroid holidays" (short breaks) when possible to minimize side effects 1
Very potent and potent corticosteroids should be used with caution for limited periods only 1
Essential Emollient Therapy
Apply emollients liberally and frequently throughout the day, immediately after bathing, as this provides a surface lipid film that retards water loss - this is critical since two-thirds of nummular eczema patients have co-existing skin dryness 1, 4
Continue aggressive emollient use even when lesions appear controlled, as this is the cornerstone of maintenance therapy 1, 3
Use soap-free cleansers exclusively and avoid hot water, as soaps and detergents remove natural skin lipids and worsen the underlying dry skin 1, 3
Regular bathing for cleansing and hydrating the skin is recommended 1
Adjunctive Tar Preparations for Lichenified Lesions
Consider ichthammol 1% in zinc ointment or coal tar solution 1% for thick, lichenified nummular plaques, as these can be particularly useful for healing chronic lesions 5
Ichthammol paste bandages can be especially effective for lichenified eczema typical of nummular lesions 5
Coal tar does not cause systemic side effects unless used extravagantly 5
Managing Pruritus
Prescribe sedating antihistamines (such as diphenhydramine or hydroxyzine) exclusively at nighttime for severe itching, as their benefit comes from sedation rather than direct anti-pruritic effects 1, 3
Non-sedating antihistamines have no value in eczema and should not be used 1, 3
Large doses of antihistamines may be required in some patients 5
Identifying and Treating Secondary Infection
Watch for increased crusting, weeping, or pustules, which indicate secondary bacterial infection with Staphylococcus aureus - this is common in nummular eczema 1, 3
Add oral flucloxacillin as first-line antibiotic while continuing topical corticosteroids 1, 3
Do not delay or withhold topical corticosteroids when infection is present - they remain the primary treatment when appropriate systemic antibiotics are given concurrently 1
Use erythromycin for penicillin-allergic patients or when flucloxacillin resistance is present 5
If you observe grouped vesicles, punched-out erosions, or sudden deterioration with fever, suspect eczema herpeticum and initiate oral acyclovir early - this is a medical emergency 1
In ill, feverish patients, administer acyclovir intravenously 1
Proactive Maintenance Therapy to Prevent Relapse
After achieving clearance, apply topical corticosteroids twice weekly (weekend therapy) to previously affected sites to prevent relapse, as nummular eczema has a chronic and relapsing course 1, 4, 2
Weekend (proactive) therapy results in a large decrease in likelihood of relapse from 58% to 25% 2
This strategy is particularly important in nummular eczema given its documented chronic course and high relapse rate 4
Addressing Aggravating Factors
Screen for and address latent dental infections with panoramic X-ray, as odontogenic infections may be an overlooked aggravating factor in treatment-resistant nummular eczema - in one case series, 11 of 13 patients with treatment-resistant disease improved after dental treatment 6
Counsel patients to avoid emotional stress and alcohol consumption, as these are documented aggravating factors 4
Identify and address contact allergens through patch testing if indicated, with nickel being the most common allergen found in nummular eczema patients 4
Second-Line Phototherapy
For treatment-resistant cases, consider narrow band ultraviolet B (312 nm) phototherapy 1
Some concern exists about long-term adverse effects such as premature skin aging and cutaneous malignancies, particularly with PUVA 1
Systemic Therapy for Severe, Refractory Disease
Systemic corticosteroids have a limited but definite role only for tiding occasional patients through acute severe flares after exhausting all other options - they should never be used for maintenance treatment 1
For adults with nummular-like atopic dermatitis phenotype failing conventional therapy, dupilumab (monoclonal antibody against IL-4 and IL-13 receptors) showed significant improvement in disease severity, pruritus, and quality of life after 16 weeks in a multicenter study 7
Common Pitfalls to Avoid
Do not undertreat with mild potency steroids - nummular eczema's thick, lichenified plaques typically require moderate-to-potent preparations 1, 2
Patients' or parents' fears of steroids often lead to undertreatment - explain the different potencies and the benefits/risks clearly 5, 1
Do not use topical corticosteroids continuously without breaks - implement "steroid holidays" when possible 1
Do not overlook dental infections in treatment-resistant cases, as this is an easily correctable aggravating factor 6