Pathology Handbook

Cytology - Tzanck Smear

Label glass slide in pencil on the frosted end with the patients full name, UR number and date of birth.

Remove the top of the skin vesicle using a scalple.

Place the slide on top of the exposed base of the vesicle and take a direct imprint on the slide.

Immediately spray the whole of the slide with fixative from a distance of approximately 20cm.

Allow the slide to dry.

Place the slide in the Cytomailer, close, and place in a biohazard bag for transport..

Please ensure Cytology specimens are sent in a separate Biohazard bag from any accompanying Histology biopsy specimens (Formalin pots). Formalin vapour affects cytology specimen preservation.

• A positive Tzanck smear almost always indicates a diagnosis of herpes simplex virus. However, it is important to remember that other members of the herpes family can also result in a positive smear, including: herpes zoster and cytomegalovirus. The clinical manifestation should help with the diagnosis as will a culture for confirmation of HSV. 

• Tzanck smears have a sensitivity of only 50%, and that is highly dependent upon the age of the lesion. In the event of a negative smear, follow-up cultures where a specimen is available is helpful in this clinical setting.