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nummular (discoid) eczema; exudative dermatitis

Epidemiology: 1) two peaks of incidence: young adults & old age 2) most common in fall & winter 3) especially common in elderly men during the winter 4) common in individuals with a history of atopic dermatitis Pathology: - subacute inflammation with acanthosis & spongiosis Clinical manifestations: 1) chronic pruritic inflammatory dermatitis - pruritus* may be extreme 2) 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 3) excoriations may occur secondary to scratching 4) regional clusters of lesions or generalized distribution 5) predilection* for: a) lower legs (older men) b) fingers (younger female) c) on trunk & extremities of patients with dry skin [4] * images [3] * claim that lesions are NOT pruritic; MKSAP17 & 19 state they are pruritic [2] * 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: 1) bacterial culture: rule-out Staphylococcus aureus 2) IgE levels normal 3) skin biopsy Differential diagnosis: 1) epidermal dermatophytosis 2) 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 3) psoriasis 4) early stages of mycosis fungoides 5) impetigo 6) familial pemphigus Management: 1) chronic disorder, often difficult to manage 2) skin hydration 3) topical glucocorticoids 1st line [4] 4) intralesional triamcinolone 3 mg/mL 5) crude coal tar 2%; may be combined with corticosteroid preparations 6) systemic antibiotics if Staphylococcus aureus is present 7) PUVA is effective, but recurrences do occur

General

eczematous dermatitis (eczema)

References

  1. Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 68-69
  2. Medical Knowledge Self Assessment Program (MKSAP) 17, 19 American College of Physicians, Philadelphia 2015, 2022
  3. DermNet NZ. Discoid eczema. (images) http://www.dermnetnz.org/dermatitis/nummular-dermatitis.html
  4. NEJM Knowledge+ Dermatology - Leung AKC, Lam JM, Leong KF, Leung AAM, Wong AHC, Hon KL. Nummular Eczema: An Updated Review. Recent Pat Inflamm Allergy Drug Discov. 2020;14(2):146-155. PMID: 32778043 Review.