Bowleg Quick Links:  Benign Vs. Malignant | Osteosarcoma  |  Soft Tissue Sarcoma  |  Metastic Bone Disease  |  Benign Bone Tumors 

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Benign Versus Malignant Lesions

What does benign versus malignant mean?

Benign lesions form in a bone and can grow locally but do not spread to other organs to cause harm. Malignant lesions, more commonly referred to as cancer, are lesions which may form and develop in the bone but have the capacity to spread to other areas of the body and continue to grow. For bone cancers this most commonly occurs to the lungs, where growth can lead to difficulty breathing and ultimately prove fatal. A tumor is an abnormal growth of cells and does not specify if something is benign or malignant, since both benign and malignant lesions form tumors in the bone.

Who gets benign versus malignant lesions?

Benign bone lesions can be due to genetic causes, growth disturbances, or changes in a small population of cells behavior. We often don’t know why a lesion forms in a specific area of bone in a specific person, but over time physicians have developed an understanding how the lesions behave regardless of why they formed. Benign lesions usually develop during growth and development so are often diagnosed in younger patients, but asymptomatic lesions can be identified well into adulthood. 

Malignant bone lesions, or bone cancer, occurs when a cell in the bone is able to multiply without restraint and evade the body’s defenses to destroy this abnormal tissue. Bone cancer is usually caused by mutations in a person’s DNA which can be genetic, spontaneous, or induced by environmental factors. Bone cancer affects all age groups, but certain subtypes, like osteosarcoma and Ewing sarcoma are more common in children, while chondrosarcoma is more common in adults.

How is a benign versus malignant lesion diagnosed?

Lesions in the bone are usually identified on XR images but are also evident on CT and MRI scans. The images are often helpful in leading to a diagnosis, and sometimes make a particular diagnosis nearly certain. However, many lesions look quite similar and no diagnosis can be immediately made. For lesions that look concerning for cancer or are causing damage to the bone, a biopsy is performed to make a specific diagnosis. This diagnosis then guides further treatment. For lesions that do not appear cancerous or destructive, serial images over time can be obtained and compared for changes, and biopsy is often unnecessary.

How are benign versus malignant lesions treated?

Many benign lesions are stable in the bone and require no treatment. Some benign lesions or tumors can be locally aggressive and require surgical treatment to eradicate the process and prevent further damage. Malignant lesions always require treatment. Malignant lesions are usually treated with surgery to remove the tumor, but may require other forms of treatment like chemotherapy or radiation therapy as well. 

Osteosarcoma

What is osteosarcoma?

Osteosarcoma is a form of cancer that originates from within a bone. Unlike most “bone cancer” which is actually cancer from another origin like the breast, prostate or lung that spreads to bone, osteosarcoma is a malignancy of the bone itself. The cancer cells produce an immature form of bone which aid in making the diagnosis, but the bone is not functional.

Who gets osteosarcoma? 

Classic osteosarcoma is diagnosed in children, adolescents and teenagers; however older individuals can develop a form of the disease as well. When older individuals are diagnosed with osteosarcoma it is often associated with other medical conditions like Paget’s disease or the area has been treated previously with radiation therapy. 

How is osteosarcoma diagnosed?

The symptoms of osteosarcoma are typically pain near a joint, most commonly the knee, that does not remit with rest or pain medications. The pain usually increases with time and is aggravated by impact activity or merely putting weight on the extremity. An X-ray is the first step in making a diagnosis. Once there is suspicion for an osteosarcoma, referral to a physician who specializes in orthopedic oncology is recommended. 

Further imaging of the suspicious area of the bone with an MRI is then performed. These advanced images will guide the physician in performing a biopsy of the lesion. The biopsy is a surgical procedure that obtains a sample or core of the bone which can be further examined under a microscope by a pathologist. Once the diagnosis is made, further imaging studies are performed to determine if the cancer has spread elsewhere in the body. 

How is osteosarcoma treated?

The treatment of osteosarcoma is conducted by a team of doctors primary lead by an oncologist and an orthopedic surgeon. The oncologist directs the chemotherapy treatment of the disease which is indicated in most forms of osteosarcoma. The orthopedic surgeon performs the excision of the tumor and the reconstruction of the limb. There are many options for surgical treatment, so patient and family input is essential. New techniques to reconstruct the affected bone with the patient’s own live bone are possible in many circumstances, even during chemotherapy. 

After the initial chemotherapy and surgical procedures, the patient is followed over time to monitor for disease recurrence. Although any diagnosis of cancer is life altering for a patient and their family, osteosarcoma is treatable and many patients are cured of the disease. 

Soft Tissue Sarcoma

What is soft tissue sarcoma?

Soft tissue sarcoma is the generic name given to types of cancer that affect the muscle, nerves, vessels and fat in our bodies. They can develop anywhere in the body but are often diagnosed in the extremities. “Soft” simply implies they are not from the bone. The designation includes many forms of cancer that are treated similarly and often studied together. 

Who gets soft tissue sarcoma?

The spectrum of soft tissue sarcoma includes some forms which are more common in children, like rhadomyosarcoma, and some forms that predominate in older individuals, like undifferentiated pleomorphic sarcoma. There are certain medical conditions which also predispose an individual to certain forms of soft tissue sarcoma. For example, patients with neurofibromatosis are more likely to develop a malignant peripheral nerve sheath tumor. Overall these are rare cancers, representing less than 1% of adult malignancies. 

How is soft tissue sarcoma diagnosed?

Regardless of the specific diagnosis, patients usually notice an enlarging mass or lump in the arm or leg. There may be a sense of fullness compared with the opposite extremity. The mass is usually painless which leads many to ignore the mass until it reaches substantial size. X-rays are usually negative. Any suspicious mass should be referred to an oncologic surgeon, as even small masses can represent cancer and need to be managed appropriately. An MRI should be obtained of any growing mass to assess its character and true size. A biopsy is then needed to make a diagnosis. 

The biopsy can safely be performed in an office setting (using a needle) or in the operating room depending on the size and location of the mass. The biopsy is evaluated by a pathologist to determine if cancer is present since many masses, even ones with slow growth over time, may be benign. If cancer is present, additional imaging studies are performed to assess for cancer in other parts of the body. 

How is soft tissue sarcoma treated?

Treatment specifics depend on the diagnosis obtained during the biopsy. However, in general surgical excision of the mass performed by an orthopedic oncologist is an essential part of treatment. Many forms of soft tissue sarcoma are treated with radiation therapy as well, thus a radiation oncologist is usually part of the treatment team. Some forms of soft tissue sarcoma also respond to traditional chemotherapy or new emerging therapies (like immunotherapy), so a medical oncologist may also guide treatment. This team of physicians will determine and coordinate the initial treatment.  

Once completed, patients are followed closely over time to assess for any signs of recurrent cancer or side effects from the treatment. Soft tissue sarcoma is most effectively treated early so we encourage patients to seek medical attention for any concerning mass or lump. 

Metastatic Bone Disease

What is metastatic bone disease?

Metastatic bone disease occurs when one form of cancer, like breast or prostate, migrates through the body to a new site in the bone and begins to grow there as well.  The initial growth usually goes unnoticed since the bone continues to function normally. Once the cancer grows to sufficient size to weaken the stability of the bone, pain usually develops with weight bearing or activity.

Who gets metastatic bone disease?

Patients with a history of cancer are at risk for metastatic bone disease. The most common types of cancer to affect the bone are breast, prostate, lung, thyroid and kidney, however most forms of cancer can metastasize to bone, so any new bone or joint pain in a patient with a history of cancer should be evaluated. 

Bone lesions may be discovered at the time of diagnosis of the primary cancer, or they may develop years later despite thorough and appropriate treatment. Patients with a history of cancer and new abnormalities on XR are evaluated with a higher level of suspicion as a result. In some cases, the pain from a metastatic bone lesion may lead to a previously unknown diagnosis of cancer elsewhere in the body.

How is metastatic bone disease diagnosed?

Suspicious lesions in the bone can be identified with XR, CT, or MRI scans. If a patient has a history of cancer and new lesions are discovered, the patient should be evaluated by an orthopedic oncologist. Additional imaging to evaluate the entire skeleton may be warranted. The lesion is then biopsied to make the diagnosis of metastatic bone disease. A pathologist can compare the cells from the biopsy to the primary cancer to determine if there is a match. 

How is metastatic bone disease treated?

Patients diagnosed with cancer often need the care of an orthopedic surgeon because the most common cancer types—breast, prostate, lung—all have a tendency to spread to bone. Most other forms of cancer can metastasize there as well. While fighting cancer is certainly difficult enough, additional pain and limited function of the arms and legs only adds to the burden. Therefore treatment of additional sites of cancer is aimed at maximizing pain relief and return to function as efficiently as possible. 

The orthopedic surgeon will be in close communication with the treating oncologist to ensure prior therapies can continue with as little interruption as possible. Choosing an orthopedic surgeon with specific knowledge and training with cancer is important because many bone metastasis behave uniquely based on the organ they originate from. The aim is to perform as few operations as possible to meet each patient’s goals and get them back to living. It is also important to evaluate for other sites of disease that may not be symptomatic yet—if treated early larger procedures can often be avoided.

Much like the initial treatment of a cancer, treatment of metastasis is a team approach. Surgery is performed as soon as possible to stabilize the diseased bone so the recovery and rehabilitation process can begin. Treatment is then followed up with some combination of radiation therapy, chemotherapy, or bone building medications to continue the fight against the new site of disease. 

The surgical options available include plates and screws, rods or nails, and partial or full joint replacement. After a thorough discussion with the patient and involved family members the choice of treatment is individualized. For example, a common site of metastasis is around the hip joint. This can lead to pain and difficulty ambulating or even a fracture. Some lesions will require medications and radiation only. Others are scraped from the bone and stabilized with a plate or a nail, while others may be large enough to require a joint replacement. Regardless, minimizing time in the hospital yet thoroughly treating the new site of disease remains the objective.

Benign Bone Tumors

What are benign bone tumors?

Benign bone tumors are abnormal lesions in the bone which affect the architecture of the bone and are identifiable on XR or other images. While they are tumors, which means an abnormal growth of tissue, they are not cancer because they do not have the capacity to grow and cause damage in other parts of the body. 

Common benign bone tumors include non-ossifying fibroma, osteoid osteoma, fibrous dysplasia, bone cysts, ganglion cysts, osteochondroma, and enchondroma.

Who gets benign bone tumors?

Most benign bone tumors develop during growth so the majority are diagnosed in children and adolescents. How many people are affected is difficult to know because many people never seek treatment for asymptomatic lesions. Some benign tumors are inherited through families, like multiple osteochondromatosis, but the majority are spontaneous growths and it is usually unknown why one person develops one while another does not. 

How are benign bone tumors diagnosed?

The initial discovery of a benign bone tumor is usually on an XR, which may have been obtained for a completely separate reason, but a bone lesion is identified nonetheless. Many benign bone tumors have a particular appearance on XR, so no further studies are needed to make a predictive diagnosis. Some benign tumors require a CT or MRI scan to be obtained, both to aid in the diagnosis and to plan treatment. The final step in making a definitive diagnosis is with a biopsy. While the majority or benign bone tumors do not require a biopsy, some look similar enough to a malignant cancerous tumor to require this procedure. However, once a benign diagnosis is made, treatment can often proceed during the same operation. 

How are benign bone tumors treated?

There is a wide spectrum of treatment for benign bone tumors which depends on the specific diagnosis. Some tumors are indolent or quiescent, meaning they are stable in the bone and unlikely to cause problems. They can be followed over time but do not require surgery. Other tumors are more active and require surgical removal of the abnormal tissue to stop their growth and allow normal bone to fill the space previously occupied by the tumor. Other benign tumors are aggressive and may have already destroyed a substantial amount of bone prior to treatment. These require a longer surgery to both remove the tumor as well as stabilize the remaining healthy bone with an orthopedic implant (plate, screws, nail, etc). Some tumors, despite being benign, can recur in the same area, so close follow up with your surgeon over time is important.

For more information on bone tumors, visit the sections below:

Patient Stories
Case Histories & Presentations

Publications
Limb Length Discrepancy and Angular Deformity due to Benign Bone Tumors and Tumor-like Lesions, Journal of the American Academy of Orthopaedic Surgeons, March 2021, Taylor J. Reif, MD, Julia Matthias, Austin T. Fragomen, MD, and S. Robert Rozbruch, MD