canis - Articles
Skin: neoplasia
Introduction
- Skin mass of variable appearance depending on site and type.
- Solitary or multiple.
- Malignant are typically characterized by sudden onset of rapidly growing mass. Ulceration can be frequently seen in malignant tumors.
Incidence
- Approximately 30% of total canine tumors.
- Incidence of various types of tumors is somewhat affected by geographical location for tumors that are linked to UV exposure.
- On average:
- 55% are mesenchymal.
- 40% are epithelial.
- 5% melanocytic..
Presenting signs
Epithelial
- Basal cell carcinoma: common.
- Squamous cell carcinoma: common.
- Papilloma: common.
- Adnexal:
- Modified apocrine/ceruminous.
- Apocrine/sweat gland: rare.
- Sebaceous: common.
- Hair matrix/follicle: rare.
- Perianal: common in unspayed females.
Mesenchymal
- Fibrosarcoma: common.
- Fibroma: rare.
- Lipoma: the most common tumor in dogs.
- Hemangioma/hemgiosarcoma: uncommon.
- Malignant fibrous histiocytoma: rare, except for vaccine-associated.
Canine round cell tumors
- Melanocytic tumor: uncommon.
- Mast cell tumor: common, reported to account for approximately 21% of all canine skin tumors.
- Histiocytomas: common skin tumors of dogs:
- One retrospective study over a 9-year period (1980-1989) showed that 5.5% of all cutaneous neoplasms were histiocytomas.
- Plasmacytomas: rare.
- Transmissible venereal tumors:
- It is enzootic in many areas of the world including the southern United States.
- Cutaneous lymphoma: while lymphoma is a common cancer in dogs, the cutaneous form is very rare and accounts for only 3-8% of all canine lymphomas.
Other tumors
- Metastatic skin lesions: uncommon.
- Sebaceous gland hyperplasia Sebaceous gland: hyperplasia / neoplasia : very common.
Age predisposition
- In general, skin tumors are seen in older dogs (9-10 years).
- Histiocytomas are most scommon in young dogs. Mean age of incidence being <3 years.
- Transmissable venereal tumors are usually seen in young, sexually active dogs from an environment with a high concentration of free roaming dogs with poor control of reproduction.
Breed/Species predisposition
- Breeds with highest risk for developing skin tumors include Boxers Boxer , Scottish terriers Scottish Terrier , Golden retrievers Retriever: Golden , Kerry Blue Terriers Kerry Blue Terrier , Basset Hounds Basset Hound , and Bull Mastiffs Bullmastiff.
- Histiocytomas are more common in certain breeds of dogs such as flat-coated retreivers Retriever: Flat-coated that had a 25% incidence of histiocytomas.
Pathogenesis
Etiology
- Squamous cell carcinoma: exposure to sunlight and papilloma viruses. Development of squamous cell carcinoma is typically preceded by actinic keratosis.
- Papilloma: papilloma viruses Papillomavirus that are transmitted by contact. Infection typically occurs when skin is damaged. Young or immunosuppressed dogs appear to be at increased risk.
- Transmissible venereal tumors (TVT) are contagious, sexually transmitted tumors of dogs. Transmitted by direct contact wherein viable tumor cells are seeded onto mucous membranes.
- Hemangiosarcoma and melanomas are also thought to be linked to UV exposure.
- Others: unknown.
Pathophysiology
- Primary mass may cause problems if very large or becomes ulcerated, secondarily infected or is at an irritaing site, eg eyelid Eyelid: neoplasia.
- May be erosive or disfiguring. If malignant, may spread to local lymph nodes and/or distant sites.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Stanclift R M & Gilson S D (2008) Evaluation of neoadjuvant prednisone administration and surgical excision in treatment of cutaneous mast cell tumors in dogs. JAVMA 232 (1), 53-62 PubMed.
- Pakhrin B, Kang M S, Bae I H, Park M S, Jee H, You M H, Yoon B I, Choi Y K & Kim D Y (2007) Retrospective study of canine cutaneous tumors in Korea. J Vet Sci 8 (3), 229-236 PubMed.
- Mukaratirwa S, Chipunza J, Chitanaga S, Chimonyo M, Bhebhe E (2005) Canine cutaneous neoplasm: prevalence and influence of age, sex and site on the presence and potential malignancy of cutaneous neoplasms in dogs from Zimbabwe. J S Afr Vet Assoc 76 (2), 59-62 PubMed.
- Kaldrymidou H, Leontides L, Koutinas S F, Saridomichelakis M N & Karayannopoulou M (2002) Prevalence, distribution and factors associated with the presence and the potential for malignancy of cutaneous neoplasms in 174 dogs admitted to a clinic in northern Greece. J Vet Med A Physiol Pathol Clin Med 49 (2), 87-91 PubMed.
- Morris J S, Bostock D E, McInnes E F, Hoather T M, Dobson J M (2000) Histopathological survery of neoplasms in flat-coated retrievers, 1990 to 1998. Vet Rec 147 (11), 291-295 PubMed.