nummular (discoid) eczema; exudative dermatitis

Epidemiology

• two peaks of incidence: young adults & old age
• most common in fall & winter
• especially common in elderly men during the winter
• common in individuals with a history of atopic dermatitis

Pathology

• subacute inflammation with acanthosis & spongiosis

Clinical manifestations

• chronic pruritic inflammatory dermatitis
  • pruritus* may be extreme
• coin-shaped lesions
  • hence the term nummular from the Latin: nummularis 'like a coin'
  • lesions often > 4-5 cm in diameter
  • round plaques consisting of small vesicles* & papules on an erythematous base
    • plaques may become exudative & crust
  • annular scaly patches & plaques
• excoriations may occur secondary to scratching
• regional clusters of lesions or generalized distribution
• predilection* for:
  • lower legs (older men)
  • fingers (younger female)
  • on trunk & extremities of patients with dry skin
    • most lesions appear on the trunk & legs (including younger females)

* images

* claim that lesions are NOT pruritic; MKSAP17,19 &20 state they are pruritic

* claim that lesions are NOT vesicular

* coin-shaped jewelry can produce coin-shaped lesions of contact dermatitis due to nickel with predilection for wrists & neck where jewelry is worn

Laboratory

• bacterial culture: rule-out Staphylococcus aureus
• IgE levels normal
• skin biopsy

Differential diagnosis

• epidermal dermatophytosis
• allergic contact dermatitis
  • coin-shaped jewelry can produce coin-shaped lesions of contact dermatitis due to nickel with predilection for wrists & neck where jewelry is worn
• psoriasis
  • Guttate psoriasis usually occurs in children
    • rapid appearance of erythematous papules, most commonly on the trunk with extension into the arms & legs.
• early stages of mycosis fungoides
• impetigo
• familial pemphigus
• discoid lupus erythematosus
  • tends to appear on sun-exposed areas
  • presents as hypo- or hyperpigmented patches or plaques, with erythema during active disease
  • lesions generally asymptomatic, but may be slightly pruritic
• pityriasis versicolor
  • minimally scaly, hyper- or hypopigmented oval macules on the trunk & arms

Management

• chronic disorder, often difficult to manage
• skin hydration
• topical glucocorticoids 1st line
• intralesional triamcinolone 3 mg/mL
• crude coal tar 2%; may be combined with corticosteroid preparations
• systemic antibiotics if Staphylococcus aureus is present
• PUVA is effective, but recurrences do occur

More general terms

• eczematous dermatitis (eczema)