Cytodiagnostic smears from cutaneous lesions can be a valuable aid to diagnosis. Standard histological sections show the architectural patterns of disease, while cytodiagnostic smears show the exact cell types participating in the disease process. It may be said that histology examines the "house," while cytology examines the "bricks." Cytodiagnosis can therefore be diagnostic in those skin diseases characterized either by a grossly excessive number of normal cells (as in basal-cell carcinoma or urticaria pigmentosa) or else by the presence of strictly abnormal cells (as in Bowen's disease or leukemia cutis).
The technique about to be described has been evolved in order to carry out the entire test in 10 to 15 minutes. Cytodiagnosis thus becomes a practical office procedure.
Obtaining the Specimen
Surface scrapings can be taken from erosions and ulcers. Crusts, pus, debris, and medicaments are first removed by swabbing with isotonic saline, and the cleansed