Page 118 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

Epithelial Tumours
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• Rarely, mature sebocytes may be seen amongst the modified perianal gland epithelial cells,
in both adenomas and carcinomas. These cells are heavily vacuolated.
VetBooks.ir • In some tumours, squamous metaplasia of the ductal epithelial cells can occur. In these
cases, variable numbers of anucleated squamous epithelial cells and occasionally cholesterol
crystals may be seen.

Differential diagnoses
• Perianal gland adenoma:
• Well-differentiated perianal gland carcinoma
• Perianal gland epithelioma
• Perianal gland carcinoma:
• Perianal gland adenoma
• Perianal gland epithelioma

Pearls and Pitfalls
• Perianal gland carcinoma does not always show significant cytological features of atypia
and may exfoliate well-differentiated hepatoid cells. Due to this, a more general diagnosis
of perianal gland tumour might be preferred, with the specification that adenoma is
common and carcinoma is rare.
• A single case report of a squamous cell carcinoma arising within a perianal gland aden-
oma was described in a dog. Cytology was characterized by well-differentiated perianal
gland epithelial cells and anucleated squamous epithelial cells. No atypical squamous
epithelial cells exfoliated upon aspiration.

Fig. 8.21. Dog. Perianal gland adenoma. Mature hepatoid gland cells in a cohesive uniform cluster. Wright-Giemsa.