Page 124 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

Epithelial Tumours

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Ceruminous gland adenoma and carcinoma
VetBooks.ir Tumours arising from the specialized sweat glands of the ear canal.

Clinical features
• Ceruminous gland adenoma:
• Common in both dogs and cats.
• Age: the peak incidence is between 7 and 10 years of age in both species.
• Usually exophytic masses within the external ear canal.
• They can be ulcerated and infected.
• Over-represented canine breeds: Cocker Spaniel, Shih Tzu, Toy Poodle, Pekingese.
• Ceruminous gland carcinoma:
• More common in cats than in dogs.
• Age: the peak incidence in cats is between 7 and 13 years of age; in dogs
between 10 and 12 years of age.
• Often presents as an infiltrative, erosive and ulcerated mass in the external ear
canal.
• Over-represented feline breeds: Domestic Short Hair
• Over-represented canine breeds: Bull Terrier, Shih Tzu, Cocker Spaniel, Belgian
Shepherd Dog (Malinois).

Cytological features
• Cellularity is variable.
• Background: pale basophilic, variably haemodiluted. It can contain black–blue granular
material and amorphous extracellular material corresponding to cerumen (earwax).
• Cells exfoliate in variably sized cohesive clusters. They are cuboidal, columnar or polygonal
and have a variable N:C ratio.
• Nuclei are round, small to medium sized in adenomas; larger and more pleomorphic in
carcinomas. One or multiple prominent nucleoli can be seen in carcinomas.
• The cytoplasm is usually moderate in amount and pale to moderately basophilic. It some-
times contains small black to dark green granules of secretory material.
• Mixed inflammatory cells can be found, especially if the tumour is ulcerated. These include
neutrophils and macrophages, which may contain amorphous phagosomes.
• Mitoses can be seen in carcinomas.