Overview

Nummular dermatitis, also known as nummular eczema or discoid eczema, is a chronic skin condition characterized by round or coin-shaped patches of irritated, inflamed, and itchy skin. The term “nummular” comes from the Latin word for “coin,” reflecting the typical shape of the lesions. These patches can be dry, scaly, or oozing and are often intensely itchy. Nummular dermatitis can affect individuals of all ages but is more common in adults, especially middle-aged and older men. It is not contagious, but it can cause significant discomfort and cosmetic concerns if not properly managed.

Causes

The exact cause of nummular dermatitis is not completely understood, but it is believed to result from a combination of environmental triggers and individual skin sensitivity. Common contributing factors include:

• Dry skin: Loss of skin moisture can lead to irritation and flare-ups.
• Skin injury: Scratches, insect bites, or minor wounds may trigger nummular eczema in susceptible individuals.
• Environmental factors: Cold, dry weather or excessive heat can aggravate symptoms.
• Contact allergens: Exposure to irritants such as soaps, detergents, or metals (like nickel) may trigger outbreaks.
• History of eczema: Individuals with a history of atopic dermatitis or other forms of eczema are at higher risk.
• Stress: Emotional stress can worsen symptoms in some people.
• Medications: Certain medications, like interferon or isotretinoin, have been associated with triggering nummular dermatitis.
• Alcohol consumption: Heavy alcohol use has been linked to a higher incidence in some studies.

Symptoms

The hallmark symptom of nummular dermatitis is the appearance of round or oval patches of irritated skin. Other common symptoms include:

• Red or brown coin-shaped lesions: These patches are typically well-defined and can vary in size.
• Itching: Intense itching is common, which can lead to scratching and further irritation.
• Dry, scaly skin: The lesions may appear rough, dry, and flaky.
• Oozing and crusting: In some cases, lesions may ooze clear fluid and form a crust.
• Thickened skin: With chronic scratching, the skin may become thick and leathery (lichenification).
• Common areas affected: Lesions most commonly appear on the arms, legs, hands, and torso but can occur anywhere on the body.

Diagnosis

Diagnosis of nummular dermatitis is typically made by a dermatologist through a clinical evaluation:

• Physical examination: The doctor assesses the appearance, shape, and distribution of the skin lesions.
• Medical history: Information about personal or family history of eczema, recent skin injuries, or exposure to irritants is considered.
• Skin scraping or biopsy: In uncertain cases, a small sample of skin may be taken to rule out fungal infections or other skin conditions.
• Patch testing: If contact dermatitis is suspected, patch testing may be performed to identify potential allergens.

Treatment

Treatment focuses on relieving symptoms, reducing inflammation, and preventing recurrence. Management strategies include:

• Moisturizers: Frequent application of emollients to keep the skin hydrated and prevent dryness.
• Topical corticosteroids: Anti-inflammatory creams or ointments are commonly prescribed to reduce redness and itching.
• Topical calcineurin inhibitors: Alternatives to steroids, such as tacrolimus or pimecrolimus, may be used for sensitive areas like the face.
• Antihistamines: Oral antihistamines may help control itching, especially at night.
• Wet dressings: In cases with oozing lesions, wet wraps or compresses can soothe the skin and reduce irritation.
• Antibiotics: If secondary bacterial infection is present, topical or oral antibiotics may be necessary.
• Phototherapy: In persistent or severe cases, controlled ultraviolet (UV) light therapy may be used.
• Avoiding triggers: Identifying and avoiding irritants, allergens, and harsh soaps is crucial.

Prognosis

The prognosis for nummular dermatitis varies by individual but is generally good with proper management:

• Chronic condition: Nummular dermatitis tends to be chronic or recurrent, with periods of flare-ups and remission.
• Symptom improvement: Most people experience significant improvement with consistent treatment and lifestyle adjustments.
• Potential for recurrence: Symptoms can return, especially in dry or cold weather, or after exposure to irritants.
• Minimal long-term complications: With proper care, complications like skin infections and scarring are rare.
• Good quality of life: Many individuals are able to control symptoms effectively and maintain a good quality of life with appropriate skin care routines and medical treatments.

With early diagnosis and regular treatment, nummular dermatitis can be well-controlled, allowing individuals to manage flare-ups and maintain healthy skin.