A comparison of the Tzanck smear and viral isolation in varicella and herpes zoster.

We compared the usefulness of the Tzanck smear to viral culture in patients with varicella and herpes zoster. All 11 patients with early lesions of varicella had a positive Tzanck preparation, while only seven (64%) of 11 had a positive culture. Twelve (80%) of 15 patients with zoster had a positive Tzanck preparation, while only nine (60%) of 15 had a positive culture. The predominance of the Tzanck yield over the culture is probably due to the increased difficulty in isolation of the varicella zoster virus. These results suggest that the Tzanck preparation is a valuable tool in the diagnosis of patients with varicella and zoster and offers a much more immediate answer than does viral culture, which often takes one to two weeks. These results contrast with those of our previous study of the Tzanck preparation and herpes simplex, in which the viral culture was more accurate than the Tzanck preparation.