A positive Tzanck test, showing three multinucleated giant cells ("Tzanck cells") in center.
In dermatopathology, the Tzanck test, also Tzanck smear, is scraping of an ulcer base to look for Tzanck cells. It is sometimes also called the Chickenpox skin test and the herpes skin test.
Tzanck cells (multinucleated giant cells) are found in:
It is named after Arnault Tzanck (1886–1954), a French dermatologist.