Comparative sensitivity of direct immunofluorescence on Tzanck smears and biopsy specimens in pemphigus

For the diagnosis of pemphigus group of diseases Direct Immunofluorescence (DIF) is considered as one of the important diagnostic tool, but the technique is costly, time taking and more technical. This study was planned to evaluate the DIF on Tzanck smears, which is simple, less traumatic and time saving. The sensitivity of DIF on Tzanck smears is compared with that of DIF on biopsy specimens, in the diagnosis of pemphigus vulgaris. Thirty-seven cases of pemphigus vulgaris were diagnosed on the basis of clinical, histopathological and direct immunofluorescence findings on perilesional biopsy specimens (cutaneous, n=24; oral mucosa, n=13). Direct immunofluorescence staining was performed on Tzanck smears from lesional cutaneous (n=24) and mucosal (n=13) specimens. The sensitivity of direct immunofluorescence on Tzanck smears was significantly lower than that on biopsy specimens (73% vs. 100%; p<0.01). The noted patterns of fluorescence were individual cells (n=27), clumps (n=22) and sheets of cells (n=19), similar to those previously reported. Although relatively simple, direct immunofluorescence on Tzanck smears is less sensitive as compared to standard immunofluorescence on biopsy specimens and cannot be used as a substitute to confirm the diagnosis of pemphigus. However, it can be useful as a screening test.