This is the most useful screening tool for obtaining rapid diagnostic information but the technique requires practice. Material for cytology may be collected by fine needle aspiration, impression from the lesion especially a freshly cut surface or exudate, or a scraping. The anatomical location usually dictates the best method of collection but a combination may be used.
Ulcerated surfaces allow scraping more easily than fine needle aspiration.
The more superficial scrapings should be discarded as they will represent secondary infection and contamination. Intraepidermal and dermo-epidermal nodules commonly exfoliate or contain fluid and are suitable for aspiration. The cell yield from subcutaneous nodules depends on the exfoliative characteristics of the tumour and other biopsy techniques may be more suitable. Be sure to collect any granules from discharging tracts. They are excellent cytological specimens.