Cutaneous Cytology - Touch Preparation/Impression Smears

Cutaneous Cytology

A form of exfoliative cytology useful to sample crusted or ulcerated skin lesions

Cutaneous Cytology - gaining a sample

• Crusts should be removed, and the area of interest blotted with a sterile swab

• The area can be moistened with a sterile cotton bud soaked in 0.9% saline (from a drip bag) or squeezed to encourage natural exudate formation

• A clean microscope slide is then firmly pressed onto the lesion and sample obtained

Touch Preparation/Impression Smears

• Samples can be too thick to analyse

• The method of collection can result in crushing and damage of cells 

• Only allow superficial sampling of external cells, so minimally diagnostic 

Cutaneous cytology - Taking a sample 

• Insert a 25-27g needle into a pustule, parallel to the skin to avoid involvement of deeper cells 

• Take an impression of the ruptured pustule material using a glass slide 

Cutaneous cytology - When should I do it?

• When a bacterial or yeast infection is suspected (pustules, papules, scales, ulcers, crusts) 

• Nodules or tumours 

• Otitis externa 

Cutaneous cytology - What might I find? 

• Cocci and rod-shaped bacteria 

• Inflammatory cells, eosinophils, macrophages 

• Malassezia 

• Neoplastic cells 

Swabbing - Moistening dry areas, or the swab with sterile saline can ..

Increase harvest and reduce cell damage

Swabbing - Sterile cotton tipped swabs are used to collect cytology from ..

• Skin 

• Ears 

• Mucous membrane surfaces 

Swabbing - Swabs are rolled over the area of interest to .. 

Gently collect cells for examination 

Slide evaluation - Air dried samples 

Can be stained with ‘Diff Quick’ technique and examined under oil immersion 

Slide evaluation - Tape samples

Can be adhered (sticky side down) to the slide and will act as a cover slip, stained and then examined under oil immersion

Slide evaluation - What are you looking for?

• Bacteria 

• Fungi 

• Yeasts 

• Inflammatory cells 

Malassezia Pachydermatis

• The most common yeast infection which can be both commensal and pathogenic 

• Very low risk Zoonosis documented in immuno-compromised humans 

Malassezia Pachydermatis - Commonly occurs in ..

Atopic animals with immuno-compromise, affecting the skin and ear canals 

Malassezia Pachydermatis - Presentation

Present in low numbers on normal skin, infection is indicated by increased numbers on sample