From the Research
Nummular dermatitis is a chronic, inflammatory skin condition characterized by coin-shaped, itchy patches on the skin, and treatment typically involves a combination of topical corticosteroids and moisturizers, as recommended by the most recent and highest quality study 1.
Diagnosis
The diagnosis of nummular dermatitis is mainly clinical, based on the characteristic round to oval erythematous plaques in a patient with diffusely dry skin, as noted in the study 1. Dermoscopy can reveal additional features that can be valuable for correct diagnosis. Biopsy or laboratory tests are generally not necessary, but a potassium hydroxide wet-mount examination of skin scrapings should be performed if tinea corporis is suspected.
Treatment
For mild to moderate cases:
- Apply a medium-potency topical corticosteroid (e.g., triamcinolone 0.1% ointment) twice daily for 2-3 weeks, as suggested by the study 1.
- Use a thick, fragrance-free moisturizer (e.g., petrolatum-based) at least twice daily, especially after bathing.
- Take lukewarm, short showers and pat the skin dry gently.
- Avoid known irritants and allergens. For severe cases:
- A high-potency topical corticosteroid (e.g., clobetasol 0.05% ointment) may be prescribed for short-term use, as recommended by the study 1.
- Oral antihistamines can help reduce itching, but their use should be cautious and under medical supervision.
- In persistent cases, phototherapy or systemic immunosuppressants, such as methotrexate, may be considered under medical supervision, as noted in the study 2.
Management
The exact cause of nummular dermatitis is unknown, but it's believed to be related to skin barrier dysfunction and inflammation, as mentioned in the study 1. Keeping the skin well-moisturized helps repair the skin barrier, while corticosteroids reduce inflammation and itching. Avoiding triggers and maintaining good skin care practices are crucial for managing this condition long-term. With proper treatment, nummular eczema can be cleared over a few weeks, although the course can be chronic and characterized by relapses and remissions, as noted in the study 1.