Atopic dermatitis (eczema)

The word nummular derives from the Latin word nummulus. Nummulus is the diminutive of the word nummus, that means “coin”. Therefore, nummular eczema refers to a type of eczema that presents with coin-shaped (round) areas of eczema. Nummular eczema is also referred to as discoid eczema.

Most patients with Nummular eczema presents with 1-3cm round patches of eczema that can occur anywhere on the body. The patches can either be weeping (acute eczema) or become thickened, dry and scaly (chronic eczema). The degree of itching is variable and can be severe.

There are two views regarding the cause of nummular eczema. One view sees Nummular eczema as a manifestation of another type of eczema that are simply presenting with nummular lesions. Another school of thought believes that Nummular eczema is a unique entity.

For practical purposes Nummular eczema can therefore be one of the following:

 

• An unique entity
• Atopic eczema presenting with nummular patches
• Allergic contact eczema presenting with nummular patches
• Stasis eczema presenting with nummular patches
• Asteatotic eczema presenting with nummular patches
• Primary irritant eczema presenting with nummular patches

So, how do you decide which one of the above possibilities applies in a particular patient?

To diagnose Nummular eczema as a unique entity you have to basically exclude all the other causes of eczema presenting with nummular patches.

The diagnosis of Atopic eczema is made on the basis of the diagnostic criteria for Atopic eczema (see Atopic Dermatitis article).

Allergic contact dermatitis is diagnosed through allergy testing, specifically patch testing. Common causes of Allergic contact dermatitis are nickel, chromate, balsam of Peru and fragrances.

Stasis eczema normally starts on the lower legs, around the ankles. It is often accompanied by varicose veins, lower leg swelling, brownish-red discoloration of the lower legs and sometimes also lower leg ulcers.

Asteatotic eczema mostly occurs in elderly people, especially in dry environments. It is therefore most often seen in winter when central heating results in dry air and subsequent dry skin.

Primary irritant dermatitis most frequently present on the hands, because this is the area most likely to be exposed to irritants.

Once all the above possibilities have been considered/exluded the treatment of Nummular eczema will therefore depend on the specific cause of the Nummular eczema, i.e. Allergic contact eczema, Atopic eczema, Nummular eczema as a unique entity etc.

In general however, the treatment will involve the frequent (2-5x per day) application of moisturizers. Topical Corticosteroids, Tacrolimus or Pimecrolimus can be used once or twice per day, while the nummular patches of eczema remains present. In severe cases light therapy and even oral immunosuppressive treatments might be indicated.