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a teen girl with osteosarcoma knee pain

An osteosarcoma diagnosis is usually made based on the results of several tests that are recommended by a physician after a patient seeks medical attention for the symptoms that could be attributed to a bone tumor. The most common signs of osteosarcoma are intermittent bone pain and swelling, often around a knee or upper arm, which worsen with activity. In rare cases, an osteosarcoma may weaken a bone to the point that it fractures at the tumor site. Although these symptoms aren’t always caused by cancer, it’s still important to have them promptly evaluated by a physician.

How is osteosarcoma diagnosed?

To confirm or rule out an osteosarcoma diagnosis, a physician will usually begin by discussing the patient’s symptoms, taking a complete medical history and performing a physical examination. In some cases, the bone tumor is visible or can be felt from outside the body. Because cancer can spread to the bones after developing elsewhere, a physician will also look for symptoms in other areas of the body.

If an osteosarcoma diagnosis is suspected, a physician will typically order one or more diagnostic tests, such as:

  • Imaging tests – Bone X-rays, chest X-rays, magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, bone scans and positron emission tomography (PET) scans can reveal the presence of tumors and other potentially suspicious masses.
  • Biopsies – If an imaging test suggests the presence of an osteosarcoma, a physician can perform a core needle biopsy, fine needle aspiration biopsy or surgical biopsy to remove a small sample of tumor cells and tissue. A pathologist can then evaluate the sample under a microscope and order further lab testing to confirm an osteosarcoma diagnosis and rule out infection and other types of bone cancer.
  • Blood tests – The presence of certain chemicals in the blood, such as alkaline phosphatase and lactate dehydrogenase, can provide important information about the stage of an osteosarcoma, and blood cell counts and blood chemistry tests can indicate a patient’s general level of health, both of which can be helpful for planning treatment.

What is an osteosarcoma sunburst?

Many patients who begin researching osteosarcoma diagnosis come across something known as an “osteosarcoma sunburst pattern” and wonder what it means. When a bone lesion grows too quickly, the membrane covering the affected bone’s outer surface (the periosteum) may not have enough time to lay down a new layer. As a result, the fibers connecting the membrane to the bone (Sharpey’s fibers) are stretched perpendicular to the bone. When the fibers turn into bony tissue (ossify), they can produce a pattern that’s known as a “sunburst periosteal reaction” or a “sunray periosteal reaction.”

Sunburst periosteal reactions are often caused by osteosarcoma but can also result from other conditions producing aggressive bone lesions, such as Ewing’s sarcoma and osteoblastic metastases. It’s important to distinguish a sunburst periosteal reaction from a sunburst (or honeycomb) trabeculation, which is a different type of finding indicating an intraosseous hemangioma. It’s also important to distinguish both of these sunburst patterns from the sunburst sign of meningioma vascularity.

What is a Codman triangle?

A Codman triangle (sometimes referred to as a "Codman’s triangle") is another type of periosteal reaction found through imaging that can indicate the presence of osteosarcoma. In some cases, a bone lesion will grow so quickly that it lifts the membrane surrounding the affected bone away from the bone and prevents it from forming a new layer. When that happens, only the edges of the raised membrane will harden into bony tissue, forming what appears to be a raised triangle along the lesion’s perimeter. This is known as a "Codman triangle."

As was noted above, osteosarcoma is a common cause of Codman triangles (in fact, it’s the most common cause of this pattern). Other potential causes include:

  • Chondrosarcoma
  • Ewing’s sarcoma
  • Malignant giant cell tumor
  • Metastasis
  • Undifferentiated pleomorphic sarcoma

Less commonly, a Codman triangle may form due to a nonmalignant lesion caused by active aneurysmal bone cysts, hematoma, osteomyelitis or trauma.

Moffitt Cancer Center's approach to diagnosing and treating osteosarcoma

If you're concerned that you might have osteosarcoma, it’s important that you reach out to a physician as soon as possible. Early detection and treatment help improve outcomes and quality of life for cancer in general, and especially so for an aggressive malignancy like osteosarcoma. After speaking with you and performing a thorough examination, a physician will be able to order the necessary testing—whether that includes an osteosarcoma X-ray, an osteosarcoma MRI or something else—so that you can find out what you’re dealing with and promptly proceed with treatment, if needed.

Fortunately, you can confidently rely on Moffitt Cancer Center for osteosarcoma diagnosis and treatment. Our comprehensive Sarcoma Program offers patients a full range of innovative osteosarcoma diagnosis and treatment options, including surgery, chemotherapy, radiation therapy and promising clinical trials. In recognition of our extensive research and commitment to improving cancer treatments, Moffitt has received the honor of being designated a Comprehensive Cancer Center by the National Cancer Institute.

If you've recently received an osteosarcoma diagnosis or would like more information about the condition, you can turn to the experts at Moffitt. Call 1-888-663-3488 or complete a new patient registration form online. We do not require referrals, and you can expect to be connected with a cancer expert in just one day. At Moffitt, we understand how stressful it can be waiting to find out whether you have cancer, and that’s why we’re so pleased to offer this incredibly quick turnaround time—the fastest one of any cancer hospital across the country.


American Cancer Society: Tests for Osteosarcoma
National Center for Biotechnology Information: Codman Triangle
Radiopaedia: Sunburst Appearance (Bone)