Nummular Eczema

On this page

Nummular Eczema - Coin Lesion Lowdown

  • AKA Discoid eczema; chronic, relapsing inflammatory dermatosis.
  • Key Feature: Intensely pruritic, coin-shaped (nummular) or oval, erythematous, eczematous plaques.
  • Sites: Extensor surfaces of extremities (esp. legs), trunk. Spares face/scalp.
  • Epidemiology: Peaks in men (55-65 yrs) & women (15-25 yrs, 55-65 yrs).
  • Etiology: Unknown; associations:
    • Dry skin (xerosis), winter months ↑
    • Irritants (soaps, trauma)
    • Staphylococcus aureus colonization/infection
    • Contact allergy (nickel, fragrance)
    • Medications (interferon, retinoids)
    • Atopic diathesis (less common)

Nummular eczema lesions

⭐ Nummular eczema lesions often start as papules/vesicles that coalesce into sharply demarcated, crusted, or scaling plaques, typically 1-10 cm in diameter. Central clearing may occur, resembling tinea corporis (ringworm).

Nummular Eczema - Itchy Coin Crisis

Nummular eczema lesions

  • Morphology:
    • Sharply demarcated, intensely pruritic, coin-shaped ("nummular") or discoid plaques; typically 1-10 cm.
    • Phases:
      • Acute: Erythematous base with grouped papules/vesicles; may ooze and form crusts.
      • Chronic: Drier, scaly, sometimes lichenified plaques.
  • Distribution:
    • Predominantly on extensor surfaces of extremities (especially legs).
    • Trunk and buttocks also common sites.
    • Usually spares the face and scalp.
  • Key Factors:
    • More common in older males.
    • Strong association with xerosis (dry skin).
    • Exacerbated by low humidity (winter), irritants, stress.
    • 📌 "COINS": Coin-shaped, Oozing (acute), Itchy, No central clearing, Staph. common.

⭐ Nummular eczema lesions are frequently colonized or secondarily infected with Staphylococcus aureus, which can exacerbate the condition and may require antimicrobial therapy.

Nummular Eczema - Eczema Detective Work

  • Diagnosis: Primarily clinical:
    • Characteristic coin-shaped (nummular), well-demarcated plaques.
    • Intensely pruritic; may be vesicular, oozing, or crusted.
    • Typically on extremities (esp. lower legs), trunk; often worse in winter.
  • Investigations:
    • KOH microscopy: Negative (essential to exclude tinea).
    • Skin biopsy (if diagnosis uncertain): Shows spongiotic dermatitis, acanthosis.
  • Differential Diagnosis Table:
    ConditionKey Differentiator(s)
    Tinea CorporisAnnular, central clearing, active scaly border; +ve KOH
    PsoriasisThick silvery scales, Auspitz sign; nail/joint involvement
    Atopic DermatitisStrong atopic history (personal/family); flexural lesions
    ImpetigoGolden-yellow ("honey-colored") crusts; less pruritus

⭐ > A key trigger for nummular eczema is skin dryness (xerosis); thus, emollients are crucial in management and prevention, especially in winter.

Nummular Eczema - Soothing Strategies

  • Core Principles:
    • Hydration: Liberal emollients (e.g., petrolatum).
    • Gentle Skin Care: Lukewarm baths, soap-free cleansers.
    • Avoid Irritants: Wool, harsh detergents.

⭐ For nummular eczema, potent topical corticosteroids are first-line; failure to respond adequately may indicate secondary infection or need for systemic therapy.

High‑Yield Points - ⚡ Biggest Takeaways

  • Presents as coin-shaped (nummular) or discoid plaques; intensely pruritic.
  • Commonly on extensor surfaces of extremities, especially legs; more frequent in older males.
  • Strong association with xerosis (dry skin), typically worsening in winter.
  • Acute lesions: vesicles, oozing, crusting; Chronic: dry, scaly, lichenified plaques.
  • Differentiate from tinea corporis (KOH microscopy negative).
  • Treatment: Potent topical corticosteroids and liberal use of emollients.
  • Often follows a chronic and relapsing course.

Practice Questions: Nummular Eczema

Test your understanding with these related questions

A 10-year-old boy presented with painful boggy swelling of scalp, multiple sinuses, with purulent discharge, easily pluckable hair and lymph nodes enlarged in occipital region. Which will be most helpful for diagnostic evaluation?

1 of 5

Flashcards: Nummular Eczema

1/10

_____ dermatitis is the occurrence of an eczematous ring surrounding a melanocytic nevus also known as Meyerson nevus

TAP TO REVEAL ANSWER

_____ dermatitis is the occurrence of an eczematous ring surrounding a melanocytic nevus also known as Meyerson nevus

Halo

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial