60 Hemangiosarcoma
HSA (also referred to as hemangioendothelioma or angiosarcoma) is a highly aggressive malignant neoplasm of the blood vessel endothelial cells. It is a cancer that can be found in almost any organ, but in dogs is found most often in the spleen. Other common primary anatomic locations include the right atrium, cutaneous, and subcutaneous tissues. Some forms of cutaneous/subcutaneous HSA appear to have a lower metastatic potential and less aggressive biologic behavior.
Older dogs (8 years or older) and large breed dogs (German Shepherds, Pointers, Boxers, and Labrador and Golden Retrievers) are overrepresented for the visceral forms of the disease. Some investigators have also reported an increased incidence in male dogs.
Middle-age or older dogs (4 years and older) and Whippets, Basset Hounds, and Dalmatians are overrepresented for the dermal forms of the disease. Sun exposure may contribute to the development of this form of the disease.
Splenic HSA can be categorized by a three-stage classification scheme. The stages are as follows:
Hemoperitoneum or splenic rupture is associated with a worse prognosis.
A three-stage classification scheme for canine cutaneous/subcutaneous HSA has also been proposed, with the different stages associated with differing prognoses. The stages are as follows:
Stage I tumors have been associated with a greater than 2-year median survival time with surgery alone, whereas stage II and III tumors have been associated with median survival times between approximately 6 and 10 months, respectively, when treated with surgery alone.
Owners may report the sudden onset of collapse or weakness associated with splenic tumor rupture. Cardiac HSA may result in signs of right-sided heart failure associated with pericardial effusion and tamponade. Other signs of visceral HSA depend on the anatomic location of the primary tumor or its metastases. Metastases arise most commonly in the liver, omentum, mesentery, and lungs, but can also arise in the kidney, brain, muscle, peritoneum, lymph nodes, adrenal glands, and diaphragm. The common concurrent presence of extensive coagulation abnormalities may also result in signs associated with a hemorrhagic diathesis.
With cutaneous disease, owners may report noticing a dark red to purple superficial plaquelike to raised lesion. These lesions are most commonly identified in hairless regions such as the ventral abdomen. Subcutaneous lesions can occur anywhere and can range from soft fluctuant to firm masses. Discoloration and ulceration are common with these lesions.
