Revaluing the Tzanck Test: A Comparative Study with Direct Immunofluorescence for Herpes Virus

Introduction: Tzanck Test (TT) is a sensitive method applicable to mucocutaneous lesions. Direct immunofluorescence (DIF) for Simplex Herpes Virus (HSV) is now a simple, no routine clinical laboratory practice, allows to differentiate the types of virus.

Objectives: To evaluate the diagnostic sensitivity of Tzanck test vs DIF for herpetic lesions, and to know its usefulness as a complementary diagnostic tool to clinical skin lesions in patients with erosive, vesicular, bullous and pustular lesions.

Materials and Methods: The TT was carried out in 157 lesion patient’s samples admitted to the Laboratory of Cytology of our Hospital from 1 January 2010 until 30 December 2014. Smears were stained with Giemsa and in parallel we performed DIF for HSV-1, HSV-2 and Varicella Zoster over 112 samples.

Results: Of the total samples, 40 (25%) were unsatisfactory for cytodiagnosis. The TT was positive in 60 samples (38%), of which 55 (35%) showed cytopathic effect for Herpes virus, 2 (1.6%) samples showed characteristic inclusion bodies of Molluscum contagiosum infection (Henderson-Paterson bodies), 1 (0.6%) sample showed acantholytic cells typical of Pemphigus Vulgaris, 1 (0.6%) showed morphological characteristics of Incontinentia Pigmenti and 1 (0.6%) presented immature cells of lymphoid appearance. 64 samples were positive by DIF and 58 by TT for HSV. Specificity and sensitivity for TT were 100% and 88% respectively.

Conclusion: The TT should be appreciated as a useful tool in the diagnosis of skin lesions by the rapid implementation and their ease interpretation, as well as being affordable and accessible for most cytology laboratories.