What is the most likely diagnosis for a female with multiple ulcerative lesions and multinucleated giant cells under Tzanck preparation?

The presence of multiple ulcerative lesions paired with multinucleated giant cells identified through Tzanck preparation strongly indicates a diagnosis of Herpes Simplex Virus (HSV). Tzanck smear is a diagnostic tool used primarily to detect lesions caused by HSV and varicella-zoster virus. The detection of multinucleated giant cells is characteristic of viral infections like HSV, which is known to cause vesicular lesions that can ulcerate.

In the context of the other options, Molluscum Contagiosum typically presents with dome-shaped papules and does not produce multinucleated giant cells in Tzanck preparation. Human Papilloma Virus (HPV) is associated with warts and does not typically lead to ulcerative lesions with multinucleated giant cells. Syphilis presents with various stages, but its primary lesions, such as chancres, do not demonstrate the cytological findings seen in Tzanck preparations.

Thus, the specific findings of ulcerative lesions and multinucleated giant cells strongly favor a diagnosis of Herpes Simplex Virus.