Are You Confident of the Diagnosis?

What you should be alert for in the history
Characteristic findings on physical examination

While ordinary eczema has an indistinct outline, nummular eczema presents with a sharply defined coin-shaped or oval border with a clearly defined margin (Figure 1). The lesions may resemble tinea corporis in appearance. The most common sites of nummular eczema are the arms and hands, particularly the dorsal surface of the hands and fingers. While the size of the plaques of nummular eczema vary, the average size is about that of a silver dollar. When they appear, they are at their full size, not spreading as in tinea.


Nummular dermatitis, “coin shaped” eczematous patch (Courtesy of Bryan Anderson, MD)

At times the center of the lesion fades while the borders become inflamed and vesicular. Healing lesions often are hyperpigmented, particularly in dark-skinned individuals.

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Expected results of diagnostic studies
Diagnosis confirmation

Nummular eczema is frequently misdiagnosed as tinea corporis and treated inappropriately with topical antifungals and steroid creams. Diagnosis is usually based on clinical appearance but if necessary, a potassium hydroxide examination will show negative results. Tinea corporis is confirmed by a positive KOH examination or fungal culture. Atopic dermatitis appears more as erythematous papules or eczematous plaques that blend in with the surrounding skin, instead of having a distinct annular shape.

Who is at Risk for Developing this Disease?

Eczema in its various manifestations is a common dermatologic condition that affects people in all age groups and is related to a defective skin barrier. Eczema, which involves damage to the intercellular lipids, can be exacerbated by irritating skin care products. Intercellular lipids contain ceramides that are necessary to form a waterproof barrier with the corneocytes to protect underlying skin tissues. Many of the above principles are applied in combination to successfully treat nummular eczema, asteototic eczema, and xerotic eczema.

What is the Cause of the Disease?

Nummular dermatitis is a form of eczema. Lesions often start as papules and coalesce into thicker plaques with scale. The pathophysiology of nummular dermatitis is still unclear. The dryness of the skin causes increased sensitivity to the environment. Medications such as interferon and ribavirin therapy for hepatits C have been associated with nummular lesions. Mast cells in the dermis of patients with nummular eczema have decreased chymase activity. This reduces the ability to degrade neuropeptides and proteins, decreasing the ability of the skin to reduce inflammation. It is more common in elderly patients in their sixth and seventh decade of life. It is rare in younger individuals

Systemic Implications and Complications

Pruritus and xerosis are very common coexisting conditions associated with nummular dermatitis. Its treatment will aid in overall prognosis of the disease. Occurrence often increases in the winter months of low humidity. Patients may have eczema, atopic dermatitis, or sensitive skin. Nummular lesions can become secondarily infected and may leave permanent scars. Lesions of lower extremities may take longer to heal.

Nummular eczema often accompanies an internal pathologic condition. Circumscribed or nummular eczemas may actually have a metabolic etiology such as chronic appendicitis, or chronic cholitis, pernicious anemia, diabetes, toxemia, focal infection, or a reflex action from a disordered internal organ. T-cell lymphoma may present with eczema; and adult-onset eczema may be associated with an underlying hyperproliferative malignancy. Nummular eczema may not improve until the internal condition has been treated and improved.

Treatment Options

  • General Measures

  • Corticosteroids

  • Immunomodulators

  • Antihistamines

  • Antibiotics (if secondarily infected)

Optimal Therapeutic Approach for this Disease

The plaques of nummular eczema are frequently recalcitrant to treatment, often recurring in the same site or nearby. The lesions are usually nonresponsive to local treatment, although at times they yield to fractional doses of X-ray, laser, and the application of crude coal tar. Recurrence suggests an internal cause, and the patient should be worked up to discover the etiology of this cutaneous expression of a possible internal disorder. The nummular eczema may not improve until the systemic condition has improved.

When an identifiable cause of an intractable nummular eczema is not found with an initial inquiry, it is important to further thoroughly work up and evaluate the patient.


Soak and Smear Treatment

These dermatologic conditions are common inflammatory skin conditions that cause a compromised skin barrier and may be associated with pruritus, fissuring, or scaling. In a study by Gutman et al, these conditions respond well to a “soak and smear” treatment. The treatment is a plain-water 20-minute soak followed by smearing of mid- to high-strength corticosteroid ointment such as triamcinalone 0.1% ointment onto the wet skin. The treatment is done at bedtime. A cream of the same strength (triamcinalone 0.1% cream) is also applied in the morning to the affected areas.

The patient is also educated to avoid washing of the skin with soaps and to use moisturizers after any washing. This treatment is done for up to 2 weeks. In more severe cases, the patient may then use the ointment only at night for 2 more weeks. When the patient has cleared, he may be switched to the soak and smear therapy with only white petroleum jelly. Eventually the patient can go to using moisturizer lotion only after showers and before bedtime as maintenance.

In the study, the soak and smear therapy is often successfully done with the same topical corticosteroid that failed in the patient in the past when it was simply applied topically even with occlusion, but without prior soaking. In the study, if the corticosteroid was continued for a month or longer, purpura at sites of trauma, usually of the upper extremities, was seen; so it is important to do patient teaching and make the change over to petroleum jelly, and then to moisturizers.

Soaking removes crust and scale, and hydrates the damaged stratum corneum, promoting desquamation. Smearing traps the moisture in the stratus corneum and delivers the topical medication in the ointment. Smearing after showering, shorter soaks, or soaking in chlorinated pools or hot tubs does not produce the same improvements and can lead to irritation.

By using the soak and smear technique, often systemic medications can be avoided. Soak and smear therapy is usually needed for several nights to 2 weeks, then changed over to the maintenance treatment when the acute process has calmed down. The regimen should be tapered by first smearing without soaking, then use the morning moisturizer at night and during the day.

Patient education

When using the soak and smear treatment, part of the maintenance therapy is also educating the patients regarding the need to reduce the use of soap and increase the use of moisturizers. These patients may have flares of the eczema, but having been educated about the cause and treatment, they can re-do the soak and smear treatment and find relief.

Ceramides and skin function.

As reported by Coderch et al, ceramides are the major lipid present in the stratus corneum and are necessary to maintain the water permeability and barrier functions of the epidermis. Coderch and his team found that most dermatology conditions with decreased barrier function have ceramide deficiency and alteration. Therefore skin lotions with ceramides and ceramide precursors can improve the barrier function of the skin and help treat skin conditions with impaired barrier function.

Achcroft et al report that topical pimecrolimus is less effective than moderate and potent corticosteroids and 0.1% tacrolimus. In a small study by Birnie et al, no evidence of benefit was found for antimicrobial interventions for patients with atopic eczema, and it was acknowledged that further larger studies are needed to form conclusive long-term outcomes.

Many commonly used skin moisturizers do not correct the stratus corneum ceramide deficiency that causes the impaired skin barrier in inflammatory dermatoses. Since glucocorticoids and other immunosuppressive agents do have a risk of toxicity, a ceramide-dominant barrier repair emollient gives a safe treatment for atopic dermatitis and other inflammatory dermatoses that are characterized by impaired skin barrier.

Moisturizers such as Cerave were found to improve the skin barrier function. Dry skin is often linked to an impaired skin barrier, as seen in xerosis and asteototic eczema. Petrolatum and ceramides have a barrier-repairing effect, without the odors that may be found objectionable to some people; 5% urea makes skin less susceptible to breakdown and damage from sodium laurel sulfate. Treatments improving the skin barrier relieve and may even prevent episodes of many dermatologic conditions.

Staphylococcus aureus is frequently found in the lesions of patients with eczematous skin conditions. A study conducted by Gong et al found that early topical treatment of moderate-to-severe eczematous skin conditions benefited from a combination of mupiricin plus a topical corticosteroid, which also reduced colonization of S aureus

An antibiotic-corticosteroid combination and corticosteroid alone both gave good therapeutic effect in eczema and in atopic dermatitis, and both reduced colonization by S aureus. Early combined topical therapy is beneficial to patients with moderate-to-severe eczema and atopic dermatitis, and it is unnecessary to use antibiotics at later stages of disease or in mild eczema.

Some new skin care lotions and cleansers contain ceramides. In a study, Draelos compared the use of fluocinonide 0.05% cream plus ceramide-containing liquid cleansers and moisture creams versus fluocinonide 0.05% cream plus bar soap in the treatment of mild-to-moderate eczema. The study showed that the high-potency corticosteroid cream, when used with ceramide-containing skin care products, enhanced the treatment outcome in mild-to-moderate eczema when compared with the use of the corticosteroid cream used with bar soap. Therefore, ceramide-containing skin care products can help when used in the treatment regimen for mild- to-moderate eczema.

Additionally, in a study of adult patients with atopic dermatitis, Nakagawa found that the most prevalent adverse reactions to tacrolimus 0.1% ointment were local application-site irritations, which generally resolved with continued therapy. The findings suggest that 0.1% tacrolimus ointment is an effective and safe nonsteroidal therapy for adult patients with atopic dermatitis.

Immunomodulators have been shown to reduce inflammation in patients with nummular dermatitis. Pimecrolimus 1% cream inhibits production and release of inflammatory cytokines from activated T-cells by binding to cytosolic immunophilin receptor macrophilin-12, which blocks T-cell activation and cytokine release. This treatment option should be used when other treatments have not been successful. Another treatment option is tacrolimus 0.03% or 0.1% ointment (Protopic).

Antihistamines can be used to assist the patients comfort level to help them sleep easier. Hydroxyzine (a typical dose being up to 25mg orally three times a day, often just administered at night for the soporific effect) may suppress the body’s histamine activity. Careful patient monitoring must be used to avoid oversedation resulting in somnolence.

Patient Management

The main goal of therapy is to rehydrate the skin to reduce eruptions of lesions. General precautions of reducing bathing time and temperature, wearing loose clothing, and use of humidifiers are recommended. Nummular dermatitis is often recurrent and avoidance of exacerbating factors will help reduce recurrence. Prognosis is generally good if treated early and proper guidelines are followed by the patient or caretakers.

Unusual Clinical Scenarios to Consider in Patient Management

Moore et al report a case of severe and recalcitrant, generalized nummular eczema, which resulted from treatment for hepatitis C. The patient was being treated with interferon alfa-2b plus ribavirin combination therapy. The patient’s nummular eczema did not remit when the treatment was stopped. There was no history of previous dermatologic disease or atopy. There was no family history of dermatologic disease. The patient had the nummular eczema—annular, erythematous, crusted plaques on the arms and back.

After a GI consult, the patient was treated with prednisone 20mg 3 times daily with a 3-week taper and 0.05% betamethasone dipropionate ointment twice daily to the elevated plaques. While there was marked improvement of the dermatitis, the patient was unable to taper down the prednisone without recurrence of the interferon-induced eruption. Interestingly, the thigh injection sites were spared. After 6 months, the patient’s condition was able to clear with prednisone 5mg/d, which was tapered by 1mg every 2 weeks; and 0.05% betamethasone dipropionate ointment used as needed.

What is the Evidence?

Ashcroft, DM, Chen, LC, Garside, R, Stein, K, Williams, HC. “Topical pimecrolimus for eczema. Cochrane Database System Rev 2007, Issue 4. Art No: CD005500”. (This study aims to assess the effects of topical pimecrolimus as an alternative to topical corticosteroids for treating eczema and other eczematic conditions including xerosis. It was concluded that topical pimecrolimus is less effective than moderate and potent corticosteroids and 0.1% tacrolimus treatments.)

Draelos, ZD, Ertel, K, Hartwig, P, Rains, G. “The effect of two skin cleansing systems on moderate xerotic eczema”. J Am Acad Dermatol. vol. 50. 2004. pp. 883-888. (This study investigated the effect of two cleansing systems: a synthetic detergent bar soap applied with a cotton washcloth and a petrolatum-delivering body wash applied with a polyethylene puff as part of a topical treatment approach to moderate xerotic eczema.)

Gong, JQ. “Skin colonization by Staphylococcus aureus in patients with eczema and atopic dermatitis: A double-blind muliticentre randomized controlled trial”. Br J Dermatol . vol. 155. 2006. pp. 680-7. (In this study, early topical treatment of moderate-to-severe eczematous skin conditions with a combination of mupiricin plus a topical corticosteroid benefited patients and reduced colonization of S aureus, which is commonly found in patients affected by eczematous conditions.)

Gutman, AB, Kligman, AM, Sciacca, J, James, WD. “Soak and smear: A standard technique revisited”. Arch Dermatol . vol. 141. 2005. pp. 1556-9. (This study describes a simple, inexpensive, effective topical treatment with an accompanying patient educational sheet. Hydration for 20 minutes before bedtime followed by ointment application to wet skin and alteration of cleansing habits was shown to be an effective method for caring for several common skin conditions.)

Birnie, AJ. ““Interventions to reduce Staphylococcus aureus in the management of atopic eczema.””. Cochrane database of systematic reviews Online. vol. 3. 2008. (This study found no evidence of benefit for antimicrobial interventions for patients with atopic eczema, and it was acknowledged that further larger studies are needed to form conclusive long-term outcomes.)

Coderch, L, López, O, de la Maza, A, Parra, JL. “Ceramides and skin function”. Am J Clin Dermatol. vol. 4. 2003. pp. 107-29. (This article sheds light on ceramides as the major lipid present in the stratus corneum and elaborates on their ability to maintain the water permeability and barrier functions of the epidermis. Coderch and his team found that most dermatologic conditions with decreased barrier function have ceramide deficiency and alteration.)