Page 1403 - Clinical Small Animal Internal Medicine

152 Hemangiosarcoma 1341

Compared to dermal HSA which has a predisposition for nonmalignant lesions such as hematoma or hemangioma
VetBooks.ir the ventral abdomen, subcutaneous and intramuscular may have a similar appearance.
Effusions are typically serosanguinous to hemorrhagic
HSA have no predilection for location.
Hematologic abnormalities may include anemia,
Uncommon Primary Locations and samples characteristically lack clot formation.
Unlike the above forms, renal hemangiosarcoma may thrombocytopenia, schistocytes, acanthocytes, pro­
carry a more prolonged history of vague symptoms, with longed prothrombin time, prolonged activated partial
a delay of 1–2 months between onset of clinical signs thromboplastin time, and increased fibrin degradation
and diagnosis. Some dogs will have hemoperitoneum. products. Approximately 50% of all dogs with splenic
The majority present with stage I disease (nonrupture, hemangiosarcoma meet disseminated intravascular
localized). Presenting complaints include lethargy, coagulation (DIC) criteria.
anorexia, and abdominal pain. The left kidney is more Dogs with myocardial hemangiosarcoma may demon­
commonly affected. strate a decreased amplitude of the QRS complex and
Clinical signs of retroperitoneal HSA are similar to electrical alternans on ECG. A visible tumor can be
patients with the renal form. However, time to diagnosis detected with echocardiography in 65–90% of cases.
is often shorter as acute hemorrhage is more common. With renal hemangiosarcoma, over half of patients
Dogs with HSA arising from the tongue may be asymp­ are anemic. Patients may present with hematuria,
tomatic. Diagnosis often occurs as an incidental finding proteinuria, hypoproteinemia, and thrombocytopenia.
identified during routine physical exam or dental proph­ Ultrasonography often reveals a unilaterally, irregular,
ylaxis. One‐third of these dogs will have clinical signs enlarged kidney.
related to an oral mass, including bleeding from the With all forms, cytologic or histologic analysis is
mouth, difficulty swallowing or difficulty eating. Lesions required for a definitive diagnosis. Ultrasound‐guided
on physical exam are small (<2 cm) and commonly fine needle aspiration for visceral forms can be attempted
located on the ventral surface but can arise from the but is associated with a significant risk of hemorrhage
dorsal aspect as well. Up to one‐quarter of dogs can have and low sensitivity (38%). Therefore, most cases will
multiple lingual tumors. require surgical biopsy. If necessary, immunochemical
analysis for factor VIII‐related antigen (von Willebrand
Cat factor), CD31, CD34, and vimentin can be performed.
In cats, full testing, including abdominal ultrasound,
Due to the most common location being the integument, three‐view thoracic radiographs, CBC, serum biochem­
most symptoms include a red or bruised raised swelling istry and UA, is recommended regardless of primary
or mass. However, for visceral and myocardial forms, location. Echocardiography in cats may not be warranted
similar symptoms as seen in the dog can be expected. as cardiac HSA is extremely uncommon. The value of
this and other diagnostics should be determined on a
case‐by‐case basis.
Diagnosis

Complete blood count (CBC), serum biochemistry, uri­ Staging System
nalysis (UA), abdominal ultrasound, echocardiogram,
three‐view thoracic radiographs, and coagulation testing Staging describes the severity of cancer based on its size,
are recommended for most forms of HSA. With the local behavior, and presence of metastasis. This informa­
myocardial form or if an arrhythmia is present, an tion is utilized in treatment planning and in assessing
electrocardiogram (ECG) should also be pursued. The prognosis. Unfortunately, no standard staging system
exception to the above is with the dermal form. Because has been established for the cat. For the dog, a modified
of the lower metastatic rate, abdominal ultrasound, World Health Organization (WHO) tumor, node, metas­
echocardiogram and ECG may not be necessary. tasis (TNM) system is commonly used (Table 152.1).
The reader is cautioned to approach each patient on an In this classification, there are three established stages.
individual basis. For visceral HSA, stage I (T0 or T1, N0, M0) describes
A high level of suspicion for HSA can be formulated a tumor <5 cm in diameter or microscopic with no
based on ultrasonography findings (70% of splenic evidence of nodal or distant metastasis and no evidence
masses will be malignant and approximately 70% of those of rupture. Stage II (T1 or T2, N0 or N1, M0) describes
will be HSA). Additionally, HSA often, but not always, no invasion into adjacent structures with or without
appears hypoechoic, cavitated, and nonhomogene­ tumor capsule rupture, no measurable distant metastasis
ous. Nonetheless, caution must be exercised as other with or without regional lymph node involvement.