What are the other Names for this Condition? (Also known as/Synonyms)

• Discoid Eczema
• Nummular Dermatitis

What is Nummular Eczema? (Definition/Background Information)

• Nummular Eczema is a chronic skin condition that leads to the formation of coin-shaped plaques, about an inch in size. The affected areas, usually the arms and legs, present itchy skin patches with small blisters
• The condition is commonly seen in older men and younger women. The cause of Nummular Eczema is not known, however it can be triggered by trauma to the skin, skin disorders, and exposure to certain chemicals and metals
• Constant itching can result in secondary infections; there can also be emotional and psychological stress due to cosmetic issues and chronic itching
• Nummular Eczema can be treated through a combination of topical applications and oral medications, along with proper skin care and adequate skin moisturization
• The prognosis of Nummular Eczema is excellent with suitable treatment, even though the condition may recur

Who gets Nummular Eczema? (Age and Sex Distribution)

• Nummular Eczema is a common condition that is seen in both males and females; though a male predominance is observed
  • In males, most cases are observed in the age group 55-65 years
  • Among females, a much lower age group is observed; even teenage girls can be affected
• Individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Nummular Eczema? (Predisposing Factors)

Following are the risk factors for Nummular Eczema:

• Skin trauma that may be due to injuries, insect bites, or burns
• Individuals with a history (either past or present) of atopic dermatitis
• Those with dry skin are more prone to Nummular Eczema
• Use of certain medication, such as isotretinoin for acne, and interferon that is used to boost one’s immunity
• Exposure to chemicals, such as formaldehyde, and metals (nickel, chromium, and cobalt)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Nummular Eczema? (Etiology)

• Currently, the exact cause of Nummular Eczema is not well-established
• But it is known to be triggered by factors such as skin injuries, dry skin, certain skin conditions, and even medications/chemicals
• Nummular Eczema is a not a contagious condition that is caused by any pathogen. It is not an infection that spreads from one individual to another through direct or indirect physical contact

What are the Signs and Symptoms of Nummular Eczema?

The signs and symptoms of Nummular Eczema may include the following:

• It is defined by the presence of itchy, coin-shaped (meaning ‘nummular’) plaques; often, there is redness of the skin in the involved area
• The size of the plaque may be between 2-5 cm, or even greater
• The plaques consists of small papules and vesicles, which get crusty and scaly with time
• These skin lesions may be singular or many in number
• They are often observed in the extremities - the arms and legs
• Scratching may lead to breaking of skin, bleeding, and ulceration
• Nummular Eczema generally becomes worse during fall and winter (two peaks)

How is Nummular Eczema Diagnosed?

A few diagnostic tests that are performed for Nummular Eczema may include:

• Complete physical examination and evaluation of one’s medical history
• Dermoscopy: Dermoscopy is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Blood tests, to rule out other causes such as infections
• Potassium hydroxide (KOH) test: The KOH prep involves microscopic observation of skin scrapings for structures belonging to fungi
• Skin biopsy: A biopsy of the lesion is usually performed to confirm the diagnosis. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Note: A tissue biopsy is generally not necessary, but may be performed to rule out other skin conditions or infections.

A differential diagnosis may be necessary to exclude the following conditions:

• Early stages of mycoses fungoides
• Pemphigus
• Allergic contact dermatitis
• Irritant contact dermatitis
• Bacterial/fungal skin infections

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Nummular Eczema?

The complications of Nummular Eczema could include:

• Secondary infections (fungal or bacterial) on the skin surface, due to bleeding and ulceration of the skin lesions
• Permanent scarring due to repeated itching
• Emotional and psychological stress due to cosmetic issues
• Recurrence of the condition

How is Nummular Eczema Treated?

The following measures may be used to treat Nummular Eczema: 

• Taking proper skin care by avoiding the tendency to itch
• Avoiding factors or activities that can aggravate the condition
• Use of moisturizing lotions to prevent the skin from drying
• Use of topical steroidal creams and lotions
• Administration of antihistamines, if itching is due to allergic causes
• Antibiotics may be used to treat infections
• Maintaining cleanliness and proper body hygiene

How can Nummular Eczema be Prevented?

Currently, it may not be possible to prevent Nummular Eczema. Although, some triggering or aggravating factors may be controlled or avoided.

• Maintain proper hygiene, keep the skin moisturized, and avoid the tendency to itch, to help mitigate the symptoms and prevent the condition from worsening
• Clipping the nails short can be beneficial

What is the Prognosis of Nummular Eczema? (Outcomes/Resolutions)

• The prognosis of Nummular Eczema is generally excellent with appropriate treatment
• However, it is a chronic and recurrent condition; the symptoms (skin patches) may appear and disappear over time

Additional and Relevant Useful Information for Nummular Eczema:

There is no evidence to prove that dietary factors have an influence on Nummular Eczema.