| Hemangiosarcoma is a malignant tumor of blood
vessel cells. With the exception of the skin form, which can often be
eliminated by surgery, a diagnosis of hemangiosarcoma is bad news. This
tumor is associated with serious internal bleeding and rapid internal
spread. Fortunately, it is not completely without therapy options and,
as long as expectations are realistic, temporary remissions are
possible.
Hemangiosarcoma can theoretically arise from any tissue where there
are blood vessels (which amounts to anywhere in the body) but there are
three classical locations which account for most presentations:
- Skin and subcutaneous forms
- Splenic forms
- Heart-based forms
The Skin Form
The skin form of hemangiosarcoma are the best types to have as they
are the most easily removed surgically and thus have the greatest
potential for complete cure.
The skin forms of hemangiosarcoma are classified as either dermal and
subcutaneous (also called hypodermal.) The true skin form looks like a
rosy red or even black growth on the skin. This form is associated with
sun exposure and thus tends to form on non-haired or sparsely haired
skin, such as on the abdomen, or on areas with white fur. Dogs with
short white haired fur (such as Dalmatians and pit bull terriers) are
predisposed to the development of this tumor. Approximately 1/3 of cases
will spread internally in the malignant way we usually associate with
cancer so it is important to remove such growths promptly.
What To Know When a Skin Growth Biopsy Comes Back as
Hemangiosarcoma
- The biopsy report will indicate whether or not the growth was
completely excised. If the tissue completely surrounding the growth
is normal, this indicates that the growth has been removed
completely and that it should not grow back.
If one wants to be absolutely positive that no tumor spread has yet
occurred, the following non-invasive (but not inexpensive) testing is
necessary.
- Chest radiographs - hemangiosarcoma tends to spread to the
lungs. Advanced tumor spread can be picked up with this simple test.
(Spots of tumor spread must be 3cm in diameter to be large enough to
be visible on a radiograph.)
- Ultrasound of the belly - specifically the spleen. Even a small
splenic hemangiosarcoma should be detectable with ultrasound.
- Ultrasound of the heart - even a small heart-based
hemangiosarcoma should be detectable with ultrasound.
Subcutaneous or Hypodermal Hemangiosarcoma
The overlying skin is often totally normal on top of a subcutaneous
hemangiosarcoma and often the surgeon is surprised to find a dark red
blood growth under the skin when the tumor is removed.
Since up to 60% of hypodermal hemangiosarcomas spread internally the
above three tests to rule out tumor spread are more important.
- If no sign of tumor spread is found after chest radiographs have
been taken and ultrasound of the heart and belly are clear,
prognosis is substantially better than if secondary tumor is found;
however, additional treatment with chemotherapy is recommended if
cure is the goal.
- Surgery alone has been associated with a 172-day (approximately
6 months) median survival time.
Hemangiosarcoma of the Spleen
 The spleen is a fairly deep-seated abdominal organ that tends to go
unnoticed unless it develops a growth of unusual enlargement. Splenic
growths have the unfortunate tendency to break open and bleed profusely
regardless of whether they are benign or malignant. While a splenectomy
(removal of the spleen) certainly ends the prospect of this type of
life-threatening sudden bleed, splenic hemangiosarcoma is still a
rapidly spreading malignancy.
When a splenic mass is detected, it may not be possible to tell prior
to splenectomy whether or not the mass is malignant or not (though
certainly basic testing is performed in an attempt to determine this.)
Read about
splenectomy to review the details of splenic mass evaluation.
Chemotherapy after removal of the splenic hemangiosarcoma is reviewed
here so see the hemangiosarcoma link on the splenectomy page when you
are ready to return for more information.
- 25% of dogs with splenic hemangiosarcoma also have a heart-based
hemangiosarcoma.
- Survival time with surgery alone is 19 to 65 days for splenic
hemangiosarcoma.
Heart-Based Hemangiosarcoma
Like the splenic hemangiosarcoma, the heart-based hemangiosarcoma
tends to exert its life-threatening effects by bleeding.
The heart is enclosed in a sac called the pericardium. When the
hemangiosarcoma bleeds, the blood fills up the pericardium until it is
so full that the heart inside is under so much pressure that it has no
room to fill with the blood it has to pump.
On chest radiographs the heart is globoid (spherical). In fact, the
actual heart is of normal shape but all that can be seen on the
radiograph is the large round heart shadow of the pericardium filled to
capacity with blood. Ultrasound is needed to truly see the effusion.
This condition, if allowed to progress, results in an emergency
circulating collapse called a "pericardial tamponade" and can only be
relieved by tapping the pericardium with a needle and withdrawing the
excess fluid.
- 63% of heart-based hemangiosarcomas have evidence of tumor
spread at the time of their discovery.
- Survival time for surgery alone (removing the pericardium and
snipping off the heart-based hemangiosarcoma) is approximately 4
months. In a study presented in the Journal of the American
Veterinary Medical Association in February 2005, 23 dogs with this
type of tumor were studied. Of the dogs that had surgery,
approximately half of them had some sort of post-operative
complication, though most complications were minor and 87% survived
and were released to go home from the hospital. Eight of these dogs
received chemotherapy in addition to surgery and these individuals
had much longer survival times (median survival of 175 days vs. 42
days for dogs who had surgery without chemotherapy).
Chemotherapy is necessary to create a substantial improvement in
survival time. The most current protocol involves injectable Adriamycin
(Doxorubicin) every 3 weeks and oral cyclophosphamide at home for 3 days
out of the week.
Hemangiosarcoma in Cats
As cancers go in cats, hemangiosarcoma is not a common one as it is
for dogs but cats still can get hemangiosarcomas. There appear to be
four main types of hemangiosarcoma in cats:
- Dermal (in the skin)
- Subcutaneous (under the skin)
- Visceral (involving internal organs)
- Oral (usually growing from the gums)
Recent studies indicate that the dermal and subcutaneous forms are
the most common. These forms have a predisposition to developing on the
head, which suggests that sun exposure is a risk factor. For the dermal
and subcutaneous forms of feline hemangiosarcoma, surgical removal is
the chief form of therapy and is the most likely to be curative for
dermal forms. Subcutaneous hemangiosarcomas are more difficult to remove
completely and have a 60% recurrence rate after surgery. The visceral
form is the most aggressive form with approximately 30% of cats being
far gone enough to warrant euthanasia at the time of initial diagnosis
(or having already died with the diagnosis being made on a post-mortem
exam).
In dogs, adding chemotherapy to surgery has been helpful in extending
the disease-free interval. Certainly protocols are available for cats,
but so few cats have been treated that statistics comparing protocols or
even comparing surgery plus chemotherapy treatment vs. surgery alone are
not available.
One useful finding that has emerged from retrospective studies is the
significance of the mitotic figure count on the biopsy sample. A mitotic
figure is a cell that is in the process of cell division when it is
fixed in formaldehyde. Since rapid cell division is a feature of
malignancy, the number of mitotic figures seen on a slice of tissue can
indicate how aggressive a tumor is. Apparently more than 3 mitotic
figures per high power microscope field indicates a much shorter
survival time than would be achieved in a case with a smaller number of
mitotic figures. The mitotic figure count is reported by the pathologist
when the biopsy sample is read, although it may have to be specifically
requested.
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