Nummular eczema

Disease Description (Causes and Symptoms)

• Definition: Nummular eczema (coin-shaped eczema, discoid eczema) is a condition in which coin-shaped eczematous plaques (round lesions) with relatively distinct borders recur or appear in groups.
• Causes/Pathophysiology: The exact cause is unknown, but it is frequently associated with dry skin (xerosis). Changes in cutaneous sensory and inflammatory mediators, such as increased neuropeptides in the lesions, have been reported. Skin barrier damage and immune responses contribute to the pathophysiology.
• Main symptoms and findings:
  • Usually occurs as coin-shaped erythematous plaques on the lower extremities (especially below the knees), the backs of the hands, and the tops of the feet
  • Acute phase: Vesicles (blisters), papules, edema, exudation, and crusting
  • Chronic phase: Scaling and lichenification (thickened, furrowed skin)
  • Severe pruritus (itching) and the possibility of wounds and secondary infection caused by scratching
• Diagnosis: Mainly diagnosed based on the characteristic clinical presentation; when necessary, a skin biopsy may be performed to confirm histopathological findings (such as inflammation and epidermal changes).

Treatment Methods

• Skin care (basic treatment)
  • Avoid irritating soaps and cleansers, and prolonged or hot baths
  • Take short baths with lukewarm water and immediately apply a full-body moisturizer (emollient) after bathing
  • Use a humidifier in dry environments and avoid skin irritants such as wool
• Medication treatment
  • Topical steroids: Apply topical steroids with moderate to high potency (depending on steroid potency) once or twice daily; stronger preparations may be used during the acute or active phase. Be aware of side effects such as skin atrophy with long-term use.
  • Topical calcineurin inhibitors (tacrolimus, pimecrolimus): Used on the face and flexural areas or as alternatives to steroids
  • Antihistamines: For the purpose of relieving itching (mainly symptom relief)
  • In cases of secondary bacterial infection: Topical or systemic antibiotics (when wounds, abscesses, or clinical signs of infection are present)
• Treatment options for moderate to refractory cases
  • Phototherapy (narrowband UVB) and systemic immunomodulators (in severe cases)—used at the discretion of a dermatologist based on the individual patient's condition
  • The use of biologics may recently be considered for some cases of refractory atopic dermatitis/eczema, but it is not the standard first-line treatment for nummular eczema
• Precautions and risk of complications (including treatment-related risks)
  • Secondary bacterial infection caused by scratching (e.g., impetigo); complete resolution may be difficult if the condition becomes chronic
  • Long-term use of high-potency topical steroids may cause side effects such as skin atrophy, pigment changes, and telangiectasia
  • Consult a doctor about the risks and benefits before using therapeutic medications, especially systemic medications
  • Relapse is more likely if daily care (moisturizing and avoiding irritants) is not continued consistently

Checklist Before an Outpatient Visit (Including Items to Bring / Example Questions)

• Items to bring (recommended)
  • A list of all medications currently being taken (including prescription, nonprescription, and herbal medicines)
  • A history of allergies (medications, foods, patch test reactions, etc.)
  • Photos or documents of previous dermatology treatment records and test results (skin biopsy, culture results, etc.)
  • Photos showing when the symptoms began and how they have progressed (especially when symptoms worsen or improve)
  • Lifestyle information (bathing frequency, soap used, occupation, pets, humidifier use, etc.)
• Items that are useful to record in advance for the medical history
  • Symptoms (degree of itching and presence or absence of pain), seasonal or environmental triggers, and whether there was a response to previous treatment
  • Whether there are signs suggestive of infection, such as fever, enlarged lymph nodes, or oozing
• Representative photos to show the doctor during the outpatient visit (front-facing, close-up, and the condition of the skin surrounding the lesions)

Examples of General Questions to Ask the Doctor

• What are the expected effects and side effects of this treatment (medication or cream)?
• How long is the treatment expected to last, and when can I expect signs of improvement?
• What daily care measures must I follow to reduce the risk of recurrence?
• Do any of my current medications interact with this treatment?
• If a secondary infection (bacterial or fungal) is suspected, what symptoms should prompt me to contact you immediately?

Examples of Disease-Specific Questions

• How can this lesion be distinguished from a fungal infection (e.g., dermatophyte infection)? Are additional tests (culture or microscopy) needed?
• How are the potency and duration of topical steroid use determined? According to what criteria would alternative treatments to reduce steroid use (such as topical calcineurin inhibitors or phototherapy) be recommended?