Cancer and benign masses alike can form in all tissue in the body. This includes bone, and, by extension cartilage that attaches to bone. Bone tumors occur because the cells in bone suddenly or gradually begin to develop and abnormally divide quickly, forming a mass of tissue. Most bone tumors are benign (not cancerous) although there are others that are cancerous, in that they will destroy normal tissue and spread to other parts of the body. Many different bones can harbor bone tumors, and often they are found in bones that are long in shape (such as the thigh bone, the shin bone, the heel bone, and the metatarsal bones in the foot).
Benign tumors are fortunately more common than malignant tumors in bone. Benign bone tumors include osteochondroma, which is the most common benign bone tumor. This is typically seen in people under age 20, and is composed of a mass of bone covered by a cartilage cap. It can sometimes be located directly under the toenail, and can push the nail upward. Other benign tumors include the giant cell tumor, which is a tumor of the bone marrow that typically affects the leg near the knees but can be in the foot, as well as osteoid osteoma and osteoblastoma, which are similar round or oval benign masses that are within bone but can be very painful. Another benign tumor in bone, made mostly of cartilage, appears in bones of the hand and feet and is called an enchondroma.
Malignant tumors that form directly in the bone are known as primary bone sarcomas. The cause of malignant bone cancer is not readily known, but genetics, high-dose radiation therapy or cancer drugs may increase the risk of this type of cancer. The most common malignant primary bone cancer in the foot is osteosarcoma, a deadly cancer which is most common around the knee and upper arm but can be found in the foot. It is seen in younger patients between the ages of 15-25, and often presents as a warm, swollen, painful area in the limb. It has the potential to spread to the lung within 2 years. Other cancerous bone tumors include Ewing's sarcoma, a malignant bone marrow cancer which is seen in younger people (usually under the age of 10 90% of the time), multiple myeloma (another bone marrow tumor), and chondrosarcoma, which is a cancer of cartilage tissue and occurs most often in people between 40 and 70. The hip, pelvis, leg, arm, and shoulder are common sites of this particular cancer, but it can occur in the foot and can rapidly grow to become quite large.
Some malignant cancer in bones can start off from cancer elsewhere in the body. Cancer of the breast, prostate, and lung can all spread into bone, as well as other types of cancers that metastasize, or spread, within the body.
Patients may never experience symptoms with some bone tumors. The tumor may be found on X-rays on accident while looking for something else. However, many bone tumors do cause some symptoms as well as general pain. These symptoms can include dull or achy pain that may get worse with activity, night pain, fevers, night sweats, unusual swelling around a bone, and limping. Because many common bone tumors occur in kids or adolescents, swelling and warmth in a child's limb, with or without pain, should prompt a parent to have their child evaluated as soon as possible, because these can potentially be the signs of a bone tumor. Limping and unusual leg or foot pain should also be a red flag. Fortunately for everyone, bone tumors are very rare and are not usually the cause of foot or leg pain, but they do need to be excluded from the diagnosis if there is any suspicion for a tumor. Advanced imaging is often used to determine the presence, size and type of tumor, and this can include CT scans, MRI, and bone scans using a radioactive compound. Often bone biopsies are performed if there is doubt about what type of tumor is present, and prompt treatment is then begun.
Treatment of bone tumors is highly dependent on the type of tumor . Treatment can include watchful waiting in the case of some benign tumors, removal of the tumor surgically, amputation if the tumor is too large or extends outside of the bone, radiation therapy (which kills cancer cells and shrinks tumors with high-dose X-rays), and systemic chemotherapy (which kills tumor cells that have spread through the bloodstream with specialized medication). An orthopedic oncologist is the specialist who will manage most cases of bone tumors, although a podiatrist can treat many types of benign tumors in the foot and ankle through surgery if indicated.