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An Urban Experience
Hemangiosarcaoma (HSA)
HSA is an aggressive malignant cancer of transformed vascular endothelial cells. It causes local infiltration and rapid systemic metastasis. German shepherds and golden Retrievers are at greatest risk. Gross metastasis is present at diagnosis in more than 50% of cases. Excluding cutaneous cancers, it accounts for about 5% of primary cancers in the dog.
Spleen is the most common primary site, but other common sites include right atrium, liver, skin and subcutis. HSA may be solitary, multifocal in an
organ, or widely disseminated. Metastasis is typically hematogenously or via transabdominal transplantation. Metastasis is most commonly to the liver and lungs. Less common sites of metastasis include the omentum, mesentery, brain, muscle and bone. HSA is considered the most common metastatic tumor to the brain.
Diagnostic Work Up
CBC and chemistry panel: The likelihood of splenic tumor increases with anemia, nucleated RBC, abnormal RBC morphology, or splenic rupture. The anemia may be regenerative with splenic rupture depending on
the duration. Neutrophilic leukocytosis may also be present. Other abnormalities include Howell-Jolly bodies, poikilocytosis, acanthocytosis, schistocytosis and/or thrombocytopenia. Thrombocytopenia is common in 75- 97% cases and rages from mild to severe. A coagulation panel should be run if HSA is suspected.
Imaging Three-view chest radiographs are mandatory to rule out pulmonary metastasis and pleural fluid. Three-views significantly decreases the false-negative rate. Abdominal ultrasound confirms the mass and allows detection of abdominal effusion, defines splenic architecture, and provides detailed evaluation of the abdominal organs and is less affected by abdominal effusion than radiographs.
FNA and cytology: Ultrasound-guided FNA is relatively simple, cost-effective and typically a safe procedure. It is most helpful for cases where the diagnosis eliminates the need for surgery, such as lymphoma. For diffuse splenomegaly, the spleen is accessible for cytology. But even with ultrasound-guidance, if non-representative tissues are sampled, you may get a false negative of benign or reactive. In one study, only 61% of cases
did cytology match histologic diagnoses. FNA is not recommended for mixed echogenicity masses suspicious of HSA as the masses are often extremely friable so there is an increased risk of hemorrhage in addition to the low diagnostic yield due to hemodilution.
HSA effusions are serosanguinous or frank blood and usually do not clot. Unfortunately cytology is typically non-diagnostic.
Cardiac evaluation: Since 25 to 45% of dogs with splenic HSA have concurrent right atrial HSA, an echocardiogram is recommended. In my experience this is lower at presentation. Arrhythmias can occur with benign and malignant lesions.
Treatment Modalities for HSA
Treatment pearls Treatment for HSA is ideally both
local and systemic. Chemotherapy improves the MST, but HSA is still a frustrating cancer for owners and veterinarians with shorter survival times than many malignant cancers in dogs. The majority of dogs tolerates chemotherapy quite well and will maintain a good to excellent quality of life even during chemotherapy.
Treatment: Surgery
Except for lymphoma, splenectomy is the treatment of choice for splenic tumors when there is no evidence of metastasis based on staging tests. Even at surgery, it is often impossible to distinguish various diseases based on gross appearance of the spleen or liver – including hematoma, nodular hyperplasia, hemangioma and HSA. Ideally the entire spleen should be submitted fresh on cold packs or in formalin. Biopsy of normal liver is controversial and may not be useful. The abdomen should be thoroughly explored and any suspicious lesions removed or biopsied. About 25% of dogs develop arrhythmias post-op. An ECG should be monitored during and after surgery, and they usually resolve within 24-48 hours.
Treatment: Chemotherapy
The goal of chemotherapy is to achieve is to delay
the metastatic disease that develops quickly after splenectomy. Since chemotherapy improves the MST, it is considered part of the standard of care. Single agent doxorubicin and combination protocols are most common.
Recently low dose oral chemotherapy (metronomic) was comparable to conventional doxorubicin. This protocol included low dose cyclophosphamide, piroxicam and etoposide. Current studies are evaluating whether conventional chemotherapy followed by maintenance metronomic chemotherapy for VEGF-receptor kinase inhibitors such as tocerinib will improve outcome.
Prognosis: Overall the prognosis with surgery alone
is poor and reported MST in dogs treated with surgery alone ranges from 1 to 3 months, and less than 10% survives 1 year. Adjunctive chemotherapy improves the MST to 4 to 6 months, and doxorubicin-based protocols are the mainstay. Stage I, non-ruptured tumors may have an improved prognosis when chemotherapy is administered after surgery. Low grade tumors may also have a better prognosis.

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