Which finding is most characteristic of erythema multiforme major?

Which finding is most characteristic of erythema multiforme major?

• A. Target lesions with mucous membrane involvement and possible epidermal detachment
• B. Absence of mucous membrane involvement
• C. Erythema migrans
• D. Thick crusted plaques on elbows

Answer: (A)

Target lesions are the signature skin finding in erythema multiforme, and when these lesions are accompanied by mucous membrane involvement, it points to erythema multiforme major. The mucosal erosions reflect more extensive mucosal disease, which distinguishes the major form from the milder minor form that lacks mucosal involvement. In severe cases there can be some epidermal detachment, but the defining feature for EM major is the combination of target-type skin lesions with mucosal involvement. The other options describe findings not typical of EM major: absence of mucous membranes would fit EM minor, erythema migrans is associated with Lyme disease, and thick crusted plaques on elbows are not characteristic of EM.

Target lesions are the signature skin finding in erythema multiforme, and when these lesions are accompanied by mucous membrane involvement, it points to erythema multiforme major. The mucosal erosions reflect more extensive mucosal disease, which distinguishes the major form from the milder minor form that lacks mucosal involvement. In severe cases there can be some epidermal detachment, but the defining feature for EM major is the combination of target-type skin lesions with mucosal involvement. The other options describe findings not typical of EM major: absence of mucous membranes would fit EM minor, erythema migrans is associated with Lyme disease, and thick crusted plaques on elbows are not characteristic of EM.