International Academy of Cosmetic Dermatology
Tzanck preparation (also known as the Tzanck smear and named after Arnault Tzanck (1886-1954) is used to diagnosis skin infections with the herpes viruses, both herpes simplex and the zoster-varicella viruses. It involves examining under the microscope a smear of the eroded lesion for cellular material.
The key to a proper Tzanck preparation is taking cells not fluid from the floor of the blister i.e. the eroded skin or the roof i.e. the base of the detaching skin. The cells are smeared onto a slide and usually stained with Wright’s stain. Microscopically, the slide is scanned for multi-nucleated cells.
While a useful screening text, the Tzanck smear is only positive in about 50-79% of patients with a known herpetic infection.
Noah Scheinfeld, MD, JD