Tzanck smear test is used in the diagnosis of:

 # Tzanck smear test is used in the diagnosis of :

a. Pemphigus 

b. ANUG 

c. Aphthous disease 

d. Lichen planus 

The correct answer is A. Pemphigus.

Pemphigus as an entity is characterized microscopically by the formation of a vesicle or bulla entirely intraepithelially, just above the basal layer producing the distinctive suprabasilar ‘split’. Prevesicular edema appears to weaken this junction, and the intercellular bridges between the epithelial cells disappear. This results in loss of cohesiveness or acantholysis, and because of this, clumps of epithelial cells are often found lying free within the vesicular space. These have been called ‘Tzanck cells’ and are characterized particularly by degenerative changes which include swelling of the nuclei and hyperchromatic staining. These changes are particularly obvious in cytologic smears taken from early, freshly opened vesicles.