Erythema Multiforme Target Lesions

A 19-year-old college student presents with an acute symmetric rash that appeared 48 hours after a recurrent herpes simplex labialis outbreak. Examination reveals well-defined round lesions on the extensor forearms, palms, soles, knees, and dorsa of feet. The structure marked **A** in the diagram—the classical targetoid lesion with three concentric zones—is characteristic of this presentation. Which of the following best describes the pathological basis of the lesion marked **A** and the most appropriate long-term management strategy?

A 22-year-old male presents with a 3-day history of painful lesions on his hands and forearms. On examination, he has multiple well-demarcated round lesions with a dusky purpuric center, surrounded by a pale edematous ring, and an outer erythematous halo. He reports a cold sore on his lip 10 days ago. The structure marked **A** in the diagram represents the characteristic lesion morphology of this condition. Which of the following best describes the pathogenic mechanism underlying the formation of this three-zone target lesion in erythema multiforme?