Final answer:
The most likely diagnosis is Herpes zoster ophthalmicus.
Step-by-step explanation:
The most likely diagnosis for a patient presenting with a vesicular lesion around the eye and a palpable preauricular lymph node is Herpes zoster ophthalmicus. Herpes zoster ophthalmicus is caused by the reactivation of the varicella-zoster virus, which also causes chickenpox. The virus affects the ophthalmic branch of the trigeminal nerve, leading to a rash around the eye and potentially causing damage to the cornea and other ocular structures.