Telangiectatic osteosarcoma is a rare type of osteosarcoma, a bone cancer made of bone-producing cells. It makes up fewer than 4 in 100 osteosarcomas.
Telangiectatic describes widened blood vessels. Most of this tumor is made of large spaces filled with blood, separated by thin walls that contain the cancer cells. This gives the tumor a sponge-like appearance on imaging and under the microscope.
Telangiectatic osteosarcoma is a high-grade cancer. It is treated the same way as other high-grade osteosarcomas, and with modern treatment its outlook is similar.
This article explains how telangiectatic osteosarcoma is diagnosed and what your pathology report findings mean.
Telangiectatic osteosarcoma most often affects teenagers and young adults, during the years when bones grow fastest. It is about twice as common in males.
It usually develops near the ends of the long bones of the legs and arms. The most common locations are the lower end of the thigh bone and the upper end of the shin bone, near the knee. The upper end of the arm bone, near the shoulder, is also a common site.
For most people, no cause is found. Osteosarcoma is not caused by injury, although an injury sometimes draws attention to a tumor that was already there.
A small number of osteosarcomas develop in people with an inherited condition that raises the risk of cancer, such as Li-Fraumeni syndrome or hereditary retinoblastoma. Your team may discuss genetic assessment if you have a family history of cancer.
The most common symptoms are pain and swelling over the affected bone, often building over a few months. The pain may be worse at night.
Because the tumor destroys a great deal of bone, it weakens the bone more than most osteosarcomas. In about a quarter to a third of people, the bone breaks with little or no force. This is called a pathologic fracture, and it is often how the tumor is first discovered.
An aneurysmal bone cyst is a noncancerous bone tumor made of blood-filled spaces. It develops in the same age group and often in the same bones. The two can look very similar on X-ray and MRI, and sometimes under the microscope.
This is the most important challenge with this diagnosis. Telling the two apart matters because an aneurysmal bone cyst is usually treated by scraping it out of the bone. Telangiectatic osteosarcoma needs chemotherapy and a larger operation. A telangiectatic osteosarcoma mistaken for an aneurysmal bone cyst can be undertreated.
Several clues help your team separate them:
X-rays, CT, and MRI show a tumor that has destroyed bone, often with blood-filled spaces. The diagnosis is confirmed with a biopsy, in which a sample of the tumor is removed and examined by a pathologist.
The biopsy should be done at the center that will perform the final surgery. The track left by the biopsy needle has to be removed along with the tumor later, so its position affects the operation.
Because so much of this tumor is blood, a biopsy may contain mostly blood and very few tumor cells. The biopsy targets the solid areas and walls seen on imaging, where the cancer cells are found. Sometimes a second biopsy is needed.
Under the microscope, the pathologist sees large blood-filled spaces separated by thin walls. The walls contain highly abnormal cells, many of which are dividing. These cells make small amounts of immature bone, called osteoid. Finding tumor-made bone confirms that the tumor is an osteosarcoma, even when only a little is present.
Telangiectatic osteosarcoma is always a high-grade tumor. Your report may state that the tumor is high grade, or it may not give a grade at all, because the diagnosis already implies it.
Most people with telangiectatic osteosarcoma receive chemotherapy before surgery. When the tumor is removed, the pathologist examines it to see how much of it was killed by the chemotherapy. This is reported as a percentage of tumor necrosis, meaning the percentage of dead tumor.
A result of 90% or more is called a good response, and a result below 90% is called a poor response. For telangiectatic osteosarcoma, chemotherapy response is the strongest predictor of outlook. This type often responds well, and some studies show it responds better than other osteosarcomas.
A poor response does not mean treatment has failed. Many people with a poor response are still cured, and your team may adjust treatment after surgery based on this result.
Your report may describe whether the tumor has broken through the outer surface of the bone into the surrounding muscle or other soft tissue. This is called extraosseous extension, and it is common in osteosarcoma. The report may also note whether the tumor has grown into a nearby joint.
A margin is the edge of tissue cut by the surgeon. Your report will list each margin and whether the tumor reaches it. Margins for a bone tumor usually include the cut ends of the bone, the surrounding soft tissue, and any large blood vessels or nerves removed.
A pathologic fracture can spread tumor cells into the surrounding tissue. The surgeon considers this when planning how much tissue to remove.
Bone cancers are staged using the TNM system from the American Joint Committee on Cancer (AJCC), 8th edition. The tumor stage, called pT, depends on which bone is involved:
Spread to distant sites matters most. The lungs are the most common place for osteosarcoma to travel, followed by other bones. This is why a CT scan of the chest is part of the assessment at diagnosis.
Telangiectatic osteosarcoma was once thought to have a poor outlook. With modern chemotherapy and surgery, its outlook is similar to that of other high-grade osteosarcomas.
These figures describe groups of people and cannot predict what will happen to one person.
A team at a center that regularly treats bone sarcomas manages telangiectatic osteosarcoma. The team usually includes an orthopedic oncologist, a medical or pediatric oncologist, a radiologist, and a pathologist.
Radiation therapy is used mainly when surgery is not possible, because osteosarcoma does not respond well to it.