Tzanck smear

What is a Tzanck smear?

The Tzanck smear test is an economical and straightforward method that involves the examination and interpretation of individual cells (cytology).

Arnault Tzanck introduced this technique in 1947 for distinguishing between different blistering conditions.

However, this test is now less commonly used because of advancements in histology, virological culture, polymerase chain reaction (PCR), and electron microscopy.

Indications for Tzanck smear

The primary use of the Tzanck smear is in acute situations for quickly identifying a herpes infection or differentiating between Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and staphylococcal scalded skin syndrome. However, it also has applications in diagnosing various cutaneous infections and blistering diseases.

How is a Tzanck smear prepared?

Choose a new blister on the patient.

• Carefully remove the roof of the lesion using a dull scalpel blade.
• Scrape the bottom of the lesion.
• Spread the tissue onto a pristine microscope slide.
• Let it air-dry.
• Preserve the specimen with a fixative.

Advantages and disadvantages of Tzanck smear test

Initial findings from a Tzanck smear typically need validation through other methods like biopsy or PCR.

Advantages:

• Cost-effective
• Causes minimal discomfort to patients
• Rapid: valuable for initial assessments, urgent diagnoses, or recurring conditions. Early diagnosis enables prompt treatment initiation.

Disadvantages:

• Expertise is needed in slide preparation and cytology interpretation.
• False negatives can occur in both early and late stages of the disease.