Page 120 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

Epithelial Tumours
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8.5 Apocrine Gland Tumours
VetBooks.ir Sweat gland adenoma and carcinoma

Tumours arising from the apocrine and eccrine glands.

Clinical features
• Apocrine adenoma and apocrine duct adenoma:
• Common in both dogs and cats.
• Age: adult animals are more frequently affected.
• Apocrine adenoma and apocrine duct adenoma usually occur on the head and
neck in both dogs and cats. Other locations for apocrine duct adenoma in dogs
are neck, thorax and legs.
• Tumours can be localized in the dermis or subcutis and can be multilobulated
and cystic. They feel soft on palpation. Apocrine tumours with a cystic cavity
often have a bluish colour due to the dark tint of the cystic fluid.
• There is no breed predisposition for apocrine adenoma in dogs and cats.
• Over-represented breeds for apocrine duct adenoma:
• Dogs: Tibetan Terrier, Old English Sheepdog, Pyrenean Mountain Dog,
Bernese Mountain Dog and Golden Retriever.
• Cats: Persian and Himalayan cats.
• Apocrine carcinoma and apocrine duct carcinoma:
• Apocrine carcinoma is relatively common in dogs, less so in cats. Apocrine duct
carcinoma is rare in both species.
• Apocrine carcinoma usually occurs on the head, axillary and inguinal areas in
both dogs and cats.
• Tumours can be in the dermis or subcutis. Inflammation and ulceration are
possible.
• Over-represented breeds for apocrine carcinoma and duct carcinoma:
• Dogs: Norwegian Elkhound, Chow Chow, Newfoundland, Shi Tzu, Old
English Sheepdog, Australian Shepherd, Keeshond.
• Cats: Siamese cats.
• Eccrine adenoma and carcinoma:
• These tumours originate from the eccrine glands and, in dogs and cats, are con-
fined to the footpads. These tumours are very rare in both species.

Cytological features

• Apocrine adenoma and apocrine duct adenoma:
• They share similar cytological characteristics, though in duct adenomas columnar cells are
more frequently found.
• Cellularity is often low to moderate. If the aspirates are from the cystic area of the tu-
mour, the preparations might be acellular or only contain rare foamy macrophages and
scattered cholesterol crystals.
• Background: clear or pale basophilic and variably haemodiluted.