Nummular Eczema

Nummular eczema is a recurrent and chronic eruption that may appear at any age, although it is most common in people in their 60s. It does not appear to be hereditary. The coin-shaped patches or plaques can affect any part of the body, but the legs and buttocks are the most common areas. Flare-ups are typically associated with the winter season.

Clinical Manifestations ⬆ ⬇

The word “nummular” comes from the same root as “numismatic,” meaning “coin-shaped,” and indeed, the round lesions of nummular eczema often have the shape of coins.
Lesions are usually itchy eczematous patches and plaques that often occur in clusters (Fig. 13.35).
Lesions are seen mainly on the legs; less commonly, they may also arise on the arms, trunk, and buttocks. The patches or plaques sometimes clear centrally and resemble tinea corporis (“ringworm”).
Healing or resolving lesions often display postinflammatory hyperpigmentation, particularly in dark-skinned patients (Fig. 13.36).

Diagnosis ⬆

The diagnosis of nummular eczema is based on the clinical appearance and, if necessary, negative results of a KOH examination.

Differential Diagnosis

Tinea Corporis

Psoriasis

Psoriatic lesions frequently occur on elbows and knees and may have a whitish or micaceous scale.

Lichen Simplex Chronicus (see above)

Management

Nummular eczema can often be controlled by an intermediate-strength (class 3 or 4) topical corticosteroid, such as triamcinolone acetonide cream 0.1%, applied sparingly two to three times daily.
If necessary, for thicker lesions, a high-potency (class 1) topical corticosteroid, such as clobetasol cream 0.05% once or twice daily, may be used.
Recalcitrant cases may require occlusion—provided by a polyethylene wrap (Saran wrap) or Cordran tape (flurandrenolide)—or intralesional corticosteroid injections.

Helpful Hint

Nummular eczema is frequently misdiagnosed as tinea corporis (“ringworm”) and is often inappropriately treated with topical antifungals.