Small animal section: No. 17
EPITHELIAL TUMOURS FROM
THE SKIN OF DOGS AND CATS
I.
CLASSIFICATION
1. BENIGN EPITHELIAL TUMOURS
-
Epidermal
-
Papilloma
and inverted papilloma.
-
Basal cell
tumour (epithelioma)
-
Adnexal
-
Follicular tumours
Infundibular keratinising acanthoma : Infundibulum
Tricholemmoma : Isthmus & inferior follicle
Trichoblastoma : Hair matrix cells (basal cells)
Pilomatricoma : Matrix & trichogenic inner sheath
Trichoepithelioma : Matrix & trichogenic sheaths
-
Subungual - Keratoacanthoma : Nailbed
-
Sebaceous
tumours - Sebaceous, Meibomian & Hepatoid glands
Adenoma
Ductal
adenoma
Epithelioma
-
Apocrine
tumours – Apocrine, Ceruminous & Anal sac glands
Adenoma
Complex/mixed adenoma
Ductal
adenoma
-
Eccrine glands
Eccrine
sweat gland adenoma on the footpads of animals
2. MALIGNANT EPITHELIAL TUMOURS
2.1
Epidermal
Basal cell
carcinoma
Squamous cell
carcinoma (SCC) including actinic keratosis, SCC in situ, multicentric SCC and
basosquamous carcinoma
2.2
Adnexal
Malignant
pilomatricoma (carcinoma)
Sebaceous,
meibomian and hepatoid gland carcinoma
Apocrine,
cerumenous and anal sac carcinoma
2.3
Eccrine
carcinoma
2.4
Subungual (nailbed) : Subungual squamous cell carcinoma
II.
Management
1.
Surgery
Complete
surgical excision with wide margins (if possible), histological evaluation of
surgical margins and regular clinical monitoring of neoplastic sites are
indicated with malignant neoplasia. Subungual squamous cell carcinomas are best
managed by toe amputation. Surgery may be used in combination with radiation or
chemotherapy
2.
Radiation therapy
Higher
energy radiation (Cobalt and Linear Accelerator) and safer anaesthetic agents
available nowadays have led to an increased success rate in tumour control while
the sparing of normal tissue due to the fractionalisation of the total radiation
dose has led to a significant decrease in the complications of radiation
therapy. Fractionalisation of the total radiation dose is also important to
prevent repopulation by neoplastic cells at the tumour site.
Tumours of the
haematopoietic systems are the most sensitive to radiation, followed by the
epithelial tumours (carcinomas) and finally poorly responsive mesenchymal
tumours (sarcomas).
3.
Solar
protection/Environmental Control
-
Keep the
animal out of the sun between 8.30am–5.30 pm.
-
Block the
ultraviolet (UV) light in one room of the house with a UV blockout film on the
windows which however let the infrared and visible light through.
-
Use a UV
blockout bodysuit. Chemically treated lycra material is used, which blocks out
98% of UV light.
4.
Monitoring of the patient and
prognosis
Monitoring of
these patients is the responsibility of the owner together with the support of
their veterinarian. The sooner tumours are treated the better the chance of
success.
-
Cats:
usually show early stages of SCC on the non pigmented pinnae and planum nasale.
If these are treated with radiation therapy at an early stage while they are
still well differentiated, the remission/cure rates are very good (>3 years).
The more advanced the SCC however, the shorter the remission period becomes.
-
Dogs:
the breeds at risk are those having no or little pigmentation and hair
covering on the ventral abdomen or thorax. The lesions progress from actinic
keratosis to squamous cell carcinoma in
situ and then develops into an infiltrative squamous cell
carcinoma. If the lycra body suits are used at the chronic inflammatory stage
of actinic keratosis, complete resolution occurs. Radiation therapy for
actinic keratosis and SCC (together with surgery if necessary) may give
remission for a relatively long period.
For more on
radiotherapy & body suites contact :
Dr Georgina
Crewe, Fairlands,
Johannesburg
Tel
:(011) 678-3121
e-mail
:georgina.crewe@acenet.co.za
Ref:
Histological classification of epithelial and melanocytic tumours of the skin of
domestic animals : Goldschmidt et al : WHO International Histological
classification
For further information contact:
VetPath Veterinary Pathologists
P.O. Box 8464
Pretoria 0001
Tel: (012) 529 8345/6
e-mail: info@vetpath.co.za
