Fresh Vesicles, Faster Answers: Diagnostic Yield of Tzanck Cytology across Herpetic Vesicular Disorders

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Background: Herpetic vesicular disorders are commonly diagnosed clinically; however, atypical morphology and altered presentations in immunocompromised patients may cause diagnostic uncertainty. Tzanck smear offers a rapid and inexpensive bedside method for demonstrating characteristic viral cytopathic changes. Aim: To evaluate the cytomorphological features and diagnostic yield of Tzanck smear in clinically diagnosed herpes zoster, herpes labialis, genital herpes and varicella, and to examine the influence of lesion duration on smear positivity. Methods: This hospital-based observational study included 67 patients with herpetic vesicular disorders. Material obtained from the base of a fresh vesicle was examined using Leishman and haematoxylin–eosin stains, with selected smears stained by May–Grünwald–Giemsa. Multinucleated giant cells, ballooned epithelial cells and acantholytic changes were recorded. Cytological yield was compared across clinical subtypes and according to lesion duration. Results: Herpes zoster accounted for 45 cases, herpes labialis for 10, varicella for eight and genital herpes for four. Characteristic cytological changes were identified in 51 patients, giving an overall diagnostic yield of 76.1%. Positivity was 77.8% in herpes zoster, 75.0% in varicella, 75.0% in genital herpes and 70.0% in herpes labialis, without significant intergroup variation. Smear positivity was significantly higher in lesions sampled within five days than in older lesions. Conclusion: Tzanck smear is a useful rapid bedside adjunct for herpetic vesicular disorders, particularly when fresh lesions are sampled early.