Page 117 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

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Perianal gland adenoma, epithelioma and carcinoma (dog)
VetBooks.ir Tumours arising from hepatoid glands, which are modified sebaceous glands.

Clinical features
• Perianal gland tumours are very common (approximately 18% of all skin tumours).
• Three types of perianal gland tumours are described: adenoma, epithelioma and
carcinoma.
• Perianal gland adenoma is more frequent than epithelioma. Carcinoma is very rare.
• Age: 8–9 to 13 years old for perianal gland adenoma and epithelioma; 6–15 years old
for perianal gland carcinoma.
• Sex predisposition: perianal gland adenoma is androgen related and male entire dogs
are most frequently affected. Intact females are at lower risk.
• Lesions can be solitary or multiple, exophytic or endophytic and often ulcerated.
• They more frequently occur on the caudal half of the animal, particularly in the peri-
anal region, tail, hindlimbs, prepuce area, mammary areas (in female dogs) and in the
midline of thorax and dorsum.
• In perianal gland adenoma, castration may reduce the size of the mass. Perianal gland
carcinoma may occasionally metastasize to the regional lymph nodes.
• Perianal gland epithelioma is regarded as a low-grade malignancy.

Cytological features

• Cellularity is variable, often moderate to high.
• Background: clear or pale basophilic and often haemodiluted.
• Neoplastic cells exfoliate in medium-large cohesive and uniform clusters.
• Perianal gland adenoma:
• Nuclei are medium sized with a reticular chromatin and a round central prominent
nucleolus. Occasionally two to three nucleoli are seen.
• The cytoplasm is abundant, lightly to moderately amphophilic to basophilic and has a
fine grainy texture.
• Low numbers of reserve epithelial cells may be seen. They are small cuboidal epithelial
cells with small, round nuclei and scant cytoplasm.
• Anisokaryosis is mild and anisocytosis is mild, occasionally moderate. The N:C ratio
is low.
• Perianal gland epithelioma:
• Aspirates exfoliate a predominance of reserve epithelial cells that usually outnumber
the mature component.
• Nuclei are small to medium sized, round and have dense chromatin and inconspicuous
nucleoli.
• The cytoplasm is scant and pale to moderately basophilic.
• Anisokaryosis and anisocytosis are minimal.
• Perianal gland carcinoma:
• Neoplastic cells are usually still relatively well differentiated but may be in more disor-
ganized clusters. Cellular pleomorphism may occasionally be more prominent and
nuclei may contain multiple prominent, occasionally angular and variably sized nucleoli.
The N:C ratio might be reduced.