CYTOLOGY – A VALUABLE IN-HOUSE TOOL FOR DERMATOLOGY CASES
Cytology is an important and useful skill in dermatology. We use our microscope, which lives in the small room next to our consulting room, for almost every case we see.
Cytology is low cost, fast, and has immediate relevance to the management decisions of the skin case. We use it to distinguish rods, cocci and Malassezia in otitis cases with secondary infection, and to assess and monitor bacterial and Malassezia dermatitis. Research has shown that heat fixation is not necessary before staining ear sample slides. Further time can be saved by only using the third (blue/purple) component of ‘Diff Quik’ when staining acetate tape strips.
Cytology allows us to select which cases need bacterial culture and sensitivity, to choose appropriate shampoo therapy, and to make rational antibiotic choices. This last point is especially relevant in these times of antibiotic stewardship and resistant organisms. Life in a potentially post-antibiotic era is a sobering prospect.
Peering down the microscope can show us inflammatory cells - such as eosinophils and neutrophils - that narrow our differential diagnosis list, or encourage us to go for more invasive diagnostics such as biopsies in cases of pemphigus foliaceus.
It is always helpful to see something waving from the slide – Cheyletiella, Sarcoptes, Demodex (stumpy wave), Otodectes, fleas – it gives us a definitive diagnosis and something to show the owner that can motivate good compliance with a treatment plan. It is several years since we’ve seen any lice.
Good cytology requires a functioning microscope, stains that are changed frequently enough, clean glass slides and coverslips, and some cotton buds. The most important ingredient is our interest and experience, qualities that rapidly increase as we look critically at more samples.
Written by Jane Coatesworth, Head of Dermatology