Diagnostic reliability of the Tzanck smear in dermatologic diseases

Abstract

The Tzanck smear is a simple, easily applicable, rapid, and inexpensive test for the diagnosis of erosive vesiculobullous, tumoral, and granulomatous diseases. The diagnostic accuracy of the Tzanck smear is known, but its diagnostic reliability has been evaluated only in herpetic infections and basal cell carcinoma. The aim of this study was to evaluate the diagnostic reliability of the Tzanck smear in erosive vesiculobullous, tumoral, and granulomatous diseases. Patients evaluated by Tzanck smear at Başkent University Faculty of Medicine, Department of Dermatology, between February 2009 and July 2010, were included. Three dermatologists were involved in the study. Dermatologist A performed a clinical dermatologic examination, took the smear material, made a clinical diagnosis, and compared the clinical and cytological diagnoses. Dermatologists B and C evaluated the smears. Agreement between the latter two dermatologists on the cytological diagnoses was determined. In 500 patients, a total of 272 (54%) erosive vesiculobullous, 190 (38%) tumoral, and 38 (8%) granulomatous lesions were diagnosed. The diagnostic reliability of the Tzanck smear was reasonably substantial (κ = 0.59) for all types of lesions, substantial for erosive vesiculobullous (κ = 0.79) and granulomatous (κ = 0.68) lesions, and moderate (κ = 0.50) for tumoral lesions. The Tzanck smear may be used for the evaluation of erosive vesiculobullous and granulomatous lesions with brief training. However, the evaluation of tumoral lesions by Tzanck smear requires more experience.