Herpes Simplex Virus Type 1 Orolabial Infection

A 28-year-old woman presents with a 3-day history of painful blisters on her upper lip, preceded by 24 hours of tingling and burning. She reports similar recurrent episodes 3–4 times yearly, triggered by febrile illnesses, sunlight, and stress. On examination, she has a cluster of thin-walled vesicles on an erythematous base at the vermilion border, with some coalesced into shallow erosions with honey-colored crusting. A Tzanck smear is performed by scraping the floor of a fresh vesicle and staining with Wright–Giemsa. The structure marked **B** in the diagram is observed on microscopy. Which of the following best describes the diagnostic significance of this finding?