건선과 화폐양 습진

초록

Nummular eczema and psoriasis are both chronic inflammatory dermatoses commonly encountered in dermatology clinics. Due to overlapping clinical presentations, especially in chronic stages, distinguishing between the two conditions can be challenging. Nummular eczema, characterized by coin-shaped erythematous plaques often accompanied by scaling or crusts, may clinically resemble plaque psoriasis, particularly when thick scaling develops over time. Recent studies have proposed that these two entities may represent different ends of an immunological spectrum, supported by the observation of paradoxical reactions—such as eczematous eruptions following psoriasis treatment and vice versa—during advanced biologic therapies. This review compares nummular eczema and plaque psoriasis with a focus on epidemiology, clinical features, histopathological findings, and dermoscopic characteristics. While certain differentiating signs exist—such as regular dotted vessels and silvery white scales in psoriasis versus irregular vascular patterns and yellow clods in nummular eczema—atypical presentations necessitate careful history taking and diagnostic evaluation. We further explore the relationship between nummular eczema and atopic dermatitis, highlighting shared immunopathological mechanisms such as Th2-skewed responses and barrier dysfunction. Nevertheless, nummular eczema exhibits immunologic heterogeneity; some chronic or moderate-to-severe cases show Th17 or type 3 immune activation, revealing partial overlap with psoriasis. These findings suggest that nummular eczema may not simply be a clinical subtype of atopic dermatitis, but a distinct disease entity residing within a broader immunological continuum between atopic dermatitis and psoriasis. As immunologically-driven therapies evolve, refining the endotypic classification of nummular eczema will be essential for advancing precision medicine and improving therapeutic outcomes.

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