The practical use of cytology for diagnosis in dermatology.

Exfoliative cytology for diagnostic purposes is rarely used in Dermatology despite the rapid and reliable results which this procedure can offer in many clinical conditions. This simple procedure may prove advantageous in a wide range of skin diseases, including genodermatoses (Hailey-Hailey disease), infections (mainly herpetic infections, molluscum contagiosum, leishmaniasis), immune disorders (early oral pemphigus) and tumours (basal and squamous cell carcinomas, Paget disease, erythroplasia of Queyrat, and others). The specific circumstances where cytological examination provides a very helpful and practical aid to confirmation or exclusion of a clinically suspected diagnosis are briefly reviewed. Cytological patterns, along with some technical hints on how to take and stain Tzanck smears correctly, are described in connection with the diseases considered.