Angiosarcoma

by Bibianna Purgina, MD FRCPC
August 21, 2022


What is angiosarcoma?

Angiosarcoma is an aggressive type of cancer that develops from specialized endothelial cells normally found on the inside of blood vessels. The most common locations include the scalp, skin and soft tissue under the skin. Other body sites that can be affected include the breast, liver, lung and spleen.

What type of cancer is angiosarcoma?

Angiosarcoma is a type of sarcoma. Sarcomas are cancers that develop from tissues such as bones, muscles, blood vessels, and connective tissue.

What causes angiosarcoma?

There are several risk factors that can increase a person’s chance of developing angiosarcoma. The first is chronic sun exposure, which is why angiosarcomas often develop in the skin. The second is a condition called chronic lymphedema, which is swelling of tissues that can develop after the removal of lymph nodes. Finally, some angiosarcomas develop in an area that has previously been treated by radiation therapy.

What are the symptoms of angiosarcoma?

The symptoms of angiosarcoma depend on the location of the tumour. Tumours located in the skin tend to grow quickly and often feel painful to the touch. Larger tumours can lead to anemia (decreased red blood cells in the blood) and other blood abnormalities including persistent bleeding or blood clots.

How do pathologists make this diagnosis?

The first diagnosis of an angiosarcoma is usually made after a small sample of the tumour is removed in a procedure called a biopsy. The biopsy tissue is then sent to a pathologist who examines it under a microscope. After the diagnosis is made, most patients are offered surgery to completely remove the tumour.

What does angiosarcoma look like under the microscope?

When examined under the microscope, angiosarcoma is made up of abnormal appearing blood vessels. The cells lining the inside of blood vessels are called endothelial cells. The endothelial cells in angiosarcoma are larger, darker, and more variable when compared to normal endothelial cells. Pathologists describe these cells as atypical. Dividing tumour cells called mitoses are usually also seen.

Angiosarcoma
Angiosarcoma. This picture shows what an angiosarcoma looks like under the microscope.
Is angiosarcoma graded?

All angiosarcomas are aggressive tumours that commonly spread to other parts of the body regardless of the microscopic features of the tumour. For that reason, angiosarcoma is not given a tumour grade.

Why is the tumour size important for angiosarcoma?

The tumour is measured in three dimensions but only the largest dimension is typically included in your report. For example, if the tumour measures 5.0 cm by 3.2 cm by 1.1 cm, the report may describe the tumour size as 5.0 cm in the greatest dimension. Tumours less than 5 cm are associated with a better prognosis.

What does tumour extension mean for angiosarcoma?

Angiosarcomas can grow into or around organs and bones. Your pathologist will examine samples of the surrounding organs and tissues under the microscope to look for cancer cells. Any surrounding organs or tissue that contains cancer cells will be described in your report.

What does treatment effect mean for angiosarcoma?

If you received chemotherapy and/or radiation therapy before the operation to remove your tumour, your pathologist will examine all the tissue sent to pathology to see how much of the tumour is still alive (viable). Most commonly, your pathologist will describe the percentage of tumour that is dead.

What is a margin?

A margin is any tissue that was cut by the surgeon to remove the tumour from your body.  Depending on the type of surgery you have had, the margins can include bones, muscles, blood vessels, and nerves that were cut to remove the tumour from your body. All margins will be very closely examined under the microscope by your pathologist to determine the margin status. Specifically, a margin is called negative when there are no cancer cells at the edge of the cut tissue. A margin is called positive when there are cancer cells at the edge of the cut tissue. A positive margin is associated with a higher risk that the tumour will recur in the same site after treatment (local recurrence).

Margin

Were lymph nodes examined and did any contain tumour cells?

Lymph nodes are small immune organs located throughout the body. Cancer cells can travel from the tumour to a lymph node through lymphatic channels located in and around the tumour (see Lymphovascular invasion above). The movement of cancer cells from the tumour to a lymph node is called metastasis.

Many cancers can spread to the lymph nodes, but angiosarcoma does this very rarely. If lymph nodes were part of the surgery to remove your tumour, your pathologist will assess them under the microscope and report whether they are involved by tumour.

Lymph node

 

What is the pathologic stage for angiosarcoma?

​The pathologic stage for angiosarcoma is based on the TNM staging system, an internationally recognized system originally created by the American Joint Committee on Cancer. This system uses information about the primary tumour (T), lymph nodes (N), and distant metastatic disease (M)  to determine the complete pathologic stage (pTNM). Your pathologist will examine the tissue submitted and give each part a number. In general, a higher number means more advanced disease and a worse prognosis.

Tumour stage (pT) for angiosarcoma

The tumour stage for angiosarcoma varies based on the body part involved. For example, a 5-centimetre tumour that starts in the head will be given a different tumour stage than a tumour that starts deep in the back of the abdomen (the retroperitoneum). However, in most body sites, the tumour stage includes the tumour size and whether the tumour has grown into surrounding body parts.

Tumour stage for tumours starting in the head and neck:

T1 – The tumour is no greater than 2 centimetres in size.
T2 – The tumour is between 2 and 4 centimetres in size.
T3 – The tumour is greater than 4 centimetres in size.
T4 – The tumour has grown into surrounding tissues such as the bones of the face or skull, the eye, the larger blood vessels in the neck, or the brain.

Tumour stage for tumours starting on the outside of the chest, back, or stomach and the arms or legs (trunk and extremities):

T1 – The tumour is no greater than 5 centimetres in size.
T2 – The tumour is between 5 and 10 centimetres in size.
T3 – The tumour is between 10 and 15 centimetres in size.
T4 – The tumour is greater than 15 centimetres in size.

Tumour stage for tumours starting in the abdomen and organs inside the chest (thoracic visceral organs):

T1 – The tumour is only seen in one organ.
T2 – The tumour has grown into the connective tissue that surrounds the organ from which is started.
T3 – The tumour has grown into at least one other organ.
T4 – Multiple tumours are found.

Tumour stage for tumours starting in the space at the very back of the abdominal cavity (retroperitoneum):

T1 – The tumour is no greater than 5 centimetres in size.
T2 – The tumour is between 5 and 10 centimetres in size.
T3 – The tumour is between 10 and 15 centimetres in size.
T4 – The tumour is greater than 15 centimetres in size.

Tumour stage for tumours starting in the space around the eye (orbit):

T1 – The tumour is no greater than 2 centimetres in size.
T2 – The tumour is greater than 2 centimetres in size but has not grown into the bones surrounding the eye.
T3 – The tumour has grown into the bones surrounding the eye or other bones of the skull.
T4 – The tumour has grown into the eye (the globe) or the surrounding tissues such as the eyelids, sinuses, or brain.

If after microscopic examination, no tumour is seen in the resection specimen sent to pathology for examination, it is given the tumour stage pT0 which means there is no evidence of primary tumour.

If your pathologist cannot reliably evaluate the tumour size or the extent of growth, it is given the tumour stage pTX (primary tumour cannot be assessed).  This may happen if the tumour is received as multiple small fragments.

Nodal stage (pN) for angiosarcoma

Angiosarcoma is given a nodal stage between 0 and 1 based on the presence or absence of cancer cells in one or more lymph nodes.

If no cancer cells are seen in any lymph nodes, the nodal stage is N0. If no lymph nodes are sent for pathological examination, the nodal stage cannot be determined, and the nodal stage is listed as NX.  If cancer cells are found in any lymph nodes, then the nodal stage is listed as N1.

Metastasis stage (pM) for angiosarcoma

Angiosarcoma is given a metastatic stage of 0 or 1 based on the presence of cancer cells at a distant site in the body (for example the lungs). The metastatic stage can only be assigned if tissue from a distant site is submitted for pathological examination. Because this tissue is rarely present, the metastatic stage cannot be determined and is listed as MX.

The metastatic stage can only be given if tissue from a distant site is sent for pathological examination. Because this tissue is rarely present, the metastatic stage cannot be determined, and it is typically not included in your report.

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