Nummular Eczema

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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.
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Flashcards: Nummular Eczema

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

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

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