Hemangiosarcoma

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Spleen of a dog with hemangiosarcoma. Multiple raised masses are present. Image courtesy of Noah's Arkive, University of Georgia.
Heart of a dog with hemangiosarcoma. Multiple raised masses are present. Image courtesy of Noah's Arkive, University of Georgia
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Hemangiosarcoma (HSA) is a common neoplastic disease of canine blood vessels[1], resulting from malignant changes within the vascular endothelium.

Although this tumor can arise in any tissue, such as the heart, liver, brain and subcutaneous tissues, the spleen is the most common site. Hemangiosarcomas are by nature aggressive, highly metastatic and associated with a relatively poor prognosis[2].

Affected dogs are often older large-breeds and usually present with a brief history of lethargy, collapse (if splenic rupture has occurred), anemia, weight loss and intermittent anorexia[3], and are often diagnosed relatively late in the course of the disease.

Cutaneous hemangiosarcomas are the least metastatic and are associated with ultraviolet light exposure in dogs and often arise on the ventral abdomen and prepuce, where the hair coat is sparse[4]. Lingual hemangiosarcomas have also been reported, with a similar nature and metastatic rate to cutaneous hemagniosarcomas[5].

Diagnosis is usually based on presenting clinical signs supported by radiographic and ultrasonographic identification of organomegaly or an abdominal mass. Staging of hemangiosarcomas on histological appearance is not usually reflective of survival time[6].

Hematology usually reveals varying degrees of thrombocytopenia, prolonged activated partial thromboplastin time, regenerative anemia and reticulocytosis[7]. DIC may occur in up to 30% of affected dogs[8].

Definitive diagnosis requires histopathological analysis of splenic or other affected visceral organs, where hemangiosarcomas have a characteristic appearance with vascular spaces lined by elongated, plump, anaplastic endothelial cells[9]. The nuclei are large and hyperchromatic, and mitotic figures are often seen. Bone marrow biopsies are usually recommended if myelodysplasia is apparent from blood tests.

A differential diagnosis would include Von Willebrand's disease[10] and various myelodysplastic syndromes such as aplastic pancytopenia and lymphoma.

Treatment is usually limited to surgical removal of devitalised tissue, splenectomy and debulking of tissue, but metastases are often present, warranting a more conservative approach in most cases.

Cutaneous hemangiosarcomas can be successfully removed surgically with wide margins of excision. However, all primary locations except superficial cutaneous tumors have a poor long-term prognosis and surgery is only for palliative purposes in most instances.

Chemotherapy should be considered the primary treatment. Doxorubicin is the recommended drug of choice in combination with vincristine and cyclophosphamide[11]. A multidrug DAV protocol (doxorubicin, dacarbazine and vincristine combination) has shown promise, where doxorubicin and dacarbazine are administered on day 1 while vincristine is administered on days 8 and 15, with the protocol repeated every 21 days for a maximum of six cycles or until disease progression. This regimen has shown efficacious (50% response rate; 125 day survival) against canine hemangiosarcoma[12].

Etoposide and doxil may also be considered as adjuvant chemotherapeutic drugs for this disease.

The prognosis for patients with splenic hemangiosarcoma is poor despite aggressive surgery and chemotherapy, with survival times from a few weeks to 6 months in most cases[13].

Cutaneous hemangiosarcomas have a better prognosis of 1 - 2 years[14].

References

  1. Fankhauser, R (2007) University of Georgia
  2. Smith Annette N (2003) Hemangiosarcoma in dogs and cats. In: The Veterinary Clinics of North America, Small Animal Practice, Advances in Medical Oncology. W.B. Saunders Co, Philadelphia, 2003, pp:533-552
  3. Withrow SJ, MacEwen EG (2001) Small Animal Clinical Oncology, 3rd ed. W.B. Saunders Co, Philadelphia, PA, 2001, pp:639–645
  4. Ward H, et al (1994) Cutaneous hemangiosarcoma in 25 dogs: A retrospective study. J Vet Intern Med 8:345-348
  5. Burton JH et al (2012) Clinical outcome in 20 cases of lingual hemangiosarcoma in dogs: 1996-2011. Vet Comp Oncol Aug 21
  6. Brown NO, Patnaik AK, MacEwen EG (1985) Canine hemangiosarcoma: Retrospective analysis of 104 cases. J Am Vet Med Assoc 186:56-58
  7. Ng CY, Mills JN (1985) Clinical and haematological features of haemangiosarcoma in dogs. Aust Vet J 62:1-4
  8. Leifer CE, et al (1985) Hypoglycemia associated with nonislet cell tumor in 13 dogs. J Am Vet Med Assoc 186:53-55
  9. Jubb KV et al (1993) Pathology of Domestic Animals, 4th ed, vol 3. Acdemic Press Inc, San Diego. p:99
  10. Prymak C, et al (1988) Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangiosarcoma and splenic hematoma in dogs: 217 cases (1985). J Am Vet Med Assoc 193:706-712
  11. Aronsohn M (1985) Cardiac hemangiosarcoma in the dog: A review of 38 cases. J Am Vet Med Assoc 187:922-926
  12. Dervisis NG et al (2011) Treatment with DAV for advanced-stage hemangiosarcoma in dogs. J Am Anim Hosp Assoc 47(3):170-178
  13. Hosgood G (1991) Canine Hemangiosarcoma. Comp Cont Educ Small Anim Prac 13:1065-1076
  14. Sprangler WL, Culbertson MR (1992) Prevalence, type, and importance of splenic diseases in dogs: 1,480 cases (1985-1989). J Am Vet Med Assoc 15:829-834