Background: Nummular eczema may mimic diseases that present with annular configuration
and the differential diagnosis is broad.
Objective: This article aimed to provide an update on the evaluation, diagnosis, and treatment of
Methods: A PubMed search was performed in using the key terms “nummular eczema”, “discoid
eczema”, OR “nummular dermatitis”. The search strategy included meta-analyses, randomized controlled
trials, clinical trials, observational studies, and reviews. The search was restricted to English
literature. The information retrieved from the above search was used in the compilation of the present
article. Patents were searched using the key terms “nummular eczema”, “discoid eczema”, OR
“nummular dermatitis” in www.google.com/patents and www.freepatentsonline.com.
Results: Nummular eczema is characterized by sharply defined, oval or coin-shaped, erythematous,
eczematous plaques. Typically, the size of the lesion varies from 1 to 10cm in diameter. The
lesions are usually multiple and symmetrically distributed. Sites of predilection include the lower
limbs followed by the upper limbs. The lesions are usually intensely pruritic. The diagnosis is mainly
clinical based on the characteristic round to oval erythematous plaques in a patient with diffusely
dry skin. Nummular eczema should be distinguished from other annular lesions. Dermoscopy
can reveal additional features that can be valuable for correct diagnosis. Biopsy or laboratory tests
are generally not necessary. However, a potassium hydroxide wet-mount examination of skin scrapings
should be performed if tinea corporis is suspected. Because contact allergy is common with
nummular eczema, patch testing should be considered in patients with chronic, recalcitrant nummular
eczema. Avoidance of precipitating factors, optimal skin care, and high or ultra-high potency
topical corticosteroids are the mainstay of therapy. Recent patents related to the management of
nummular eczema are also discussed.
Conclusion: With proper treatment, nummular eczema can be cleared over a few weeks, although
the course can be chronic and characterized by relapses and remissions. Moisturizing of the skin
and avoidance of identifiable exacerbating factors, such as hot water baths and harsh soaps may reduce
the frequency of recurrence. Diseases that present with annular lesions may mimic nummular
eczema and the differential diagnosis is broad. As such, physicians must be familiar with this condition
so that an accurate diagnosis can be made, and appropriate treatment initiated.