Squamous cell carcinomas may occur anywhere in the skin in dogs and cats as well as other species.
They are often ulcerated and secondarily and superficially infected.
Imprints may only reveal inflammation but scrapings may reveal tumour cells but deep aspirates are often most rewarding especially as they are quite exfoliative tumours.
The features of SCC on cytology vary with their degree of differentiation.
Sometimes normal cells are apparent but most often display moderate anisokaryosis and anisocytosis.
Keratinising cells and keratin maybe found in well differentiated tumours.
Typical features are of well demarcated cell borders and polygonal when in clumps and round when individual, abundant basophilic cytoplasm and a large nucleus with clumped chromatin and prominent nucleoli (unlike maturing squamous epithelial cells).
Sometimes they are infiltrated with neutrophils and display emperipolesis (internalisation of neutrophils – Arrowhead).
The metastatic potential increases with the lack of differentiation and atypia.
First published: Fri, Jan 28 2011