HEMANGIOSARCOMA

Pathogenesis

•HSA is a malignant neoplasm arising from endothelial cells

•dermal HSA accounts for 14% of primary HSA

•vascular stasis, radiation therapy, trauma, and sun exposure are predisposing factors in humans

•HSA has been experimentally induced in dogs with UV radiation and solar radiation may be involved in spontaneous development of cutaneous HSA in dogs

Signalment

•sex predisposition: male

•breed predisposition: GSD, Boxer, Whippet, and Pit Bull Terrier

•dermal HSA is usually rapidly growing solitary, poorly circumscribed mass with early ulceration and infiltration

•≥ 1 cutaneous HSA may represent metastatic disease

•however, multicentricity is a feature of canine HSA with up to 18% of primary cutaneous HSA presenting with multiple lesions

Diagnosis

•hemostatic disorders are common and coagulation profile and bleeding times should be assessed

•staging is important to assess whether cutaneous lesions are primary or metastatic lesions from a primary HSA in the spleen, right auricle, or liver

Clinical Stage

•clinical staging is based on location within the dermis or association with the dermis:

•stage I: dermal

•stage II: hypodermal

•stage III: muscle

Treatment

•wide surgical resection for stage I HSA

•wide surgical resection (i.e., limb amputation) and adjunctive chemotherapy (i.e., doxorubicin, cyclophosphamide, and vincristine) for stage II and III HSA

•radiation therapy is ineffective

Prognosis

•prognosis is guarded

•30% metastatic rate and MST 780 days for stage I HSA

•10% metastatic rate and MST 172 days for stage II HSA

•60% metastatic rate and MST 307 days for stage III HSA

•MST for hypodermal HSA following surgery and chemotherapy: 425 days

•good prognostic factors in humans include small tumor size (< 5 cm) and lymphocytic infiltration around tumor

HEMANGIOMA

•no breed or sex predilection

•gross appearance: solitary, well circumscribed, unencapsulated, red-to-black colour, and located in subcutaneous and dermoepidermal tissue