Most people who have foot pain do not have a bone tumor, and few bone tumors are malignant (cancerous). A bone tumor develops when cells multiply abnormally within a bone. The tumor may replace healthy bone tissue or it may weaken the bone, causing a fracture. Bone tumors of the foot are rare, comprising only three to six percent of all bone tumors, and are benign in 75 to 85 percent of cases (Sarcoma, 2013). A benign bone tumor of the foot will manifest as a lump, with or without pain, whereas bone cancer is most often accompanied by pain at the location of the tumor. The World Health Organization has identified 82 different benign and malignant foot lesions. A study that looked at the differential diagnosis of foot lumps found that the toes and dorsum of the foot were the most commonly affected areas, and the heel was the least commonly affected area (Annals of The Royal College of Surgeons of England, 2007).
You should not become alarmed if you notice a lump in your foot, as the chance of a malignant bone tumor developing is quite small. However, you should have the lump examined by your primary care physician to see whether further evaluation or treatment by an orthopedist is necessary. This is especially important if your lump is painful.
Symptoms of Bone Tumor of the Foot
Bone tumors of the foot may be painless. Foot injury can cause a tumor to start hurting. Bone that is already weakened by a tumor can break, causing severe pain. In some instances, the appearance of the lump may coincide with other symptoms, such as fevers and night sweats. Pain is the most common complaint, and it is often described as a dull ache in the area of the tumor. The pain may or may not be associated with activity. Some people may awaken during the night because of the pain. If you have a bone tumor, you may have one or more of the following symptoms:
- Footwear problems
- Cosmetic concerns
- Numbness or pins and needles (paraesthesia)
Benign Bone Tumors of the Foot
The majority of bone tumors are benign. Common types of benign bone tumors include:
Simple bone cyst: This tumor occurs most often in children aged 4 to 10. The lesion remains asymptomatic unless complicated by fracture. It enlarges during skeletal growth and becomes inactive after skeletal maturity.
Osteochondroma: This tumor typically affects teenagers and young adults in their twenties, but it occasionally appears in older adults. The tumor presents as a painless lump that increases in size with the patient’s growth. It is almost always located on the metatarsals.
Enchondroma: Adults aged 20 to 40 may have this tumor, which often causes pain during activities or after injury, usually after a small fracture. A lump may not be visible or palpable. The phalanges are often affected. A giant cell tumor may be mistaken for enchondroma, and either can occur in the foot in similar locations.
Giant cell tumor: A giant cell tumor may be found on the toes, anywhere on the surface of the foot, or deep inside the foot. It always involves a tendon sheath. It often appears as a painful, firm, irregular lump in adults aged 20 to 50. The tumor grows slowly, and can reach a maximum of about 4 cm. As the tumor grows, it can cause erosion of the adjacent bone from the pressure of the tendon rubbing against it.
Malignant Bone Tumors of the Foot
Bone cancer of the foot is very rare. Certain types of malignant bone tumors of the foot are reported more than others. These tumors can be aggressive. The prognosis is usually worse in patients who present with metastatic disease. A few of the more common malignant bone tumors of the foot include:
Chondrosarcoma: This tumor may occur in adults between 40 and 70 years of age. It more commonly develops in the pelvis, femur, or shoulder. When chondrosarcoma develops in the foot, it can be difficult to distinguish from an enchondroma.
Ewing’s sarcoma: Children and adults up to 20 years of age may have Ewing’s sarcoma. The tumor may be present for many months before it becomes large enough to cause pain and swelling. The chances of survival are better for those who have a bone tumor of the forefoot than those with a bone tumor of the hindfoot.
Osteosarcoma: Osteosarcomas of the foot can easily be misdiagnosed, especially because they almost always occur in adults, whereas most cases of osteosarcoma in other parts of the body occur in teenagers. They can occur in any bone the foot, although the calcaneus is the most commonly involved bone.
Bone Tumor of the Foot Diagnosis
While evaluating a possible bone tumor of the foot, your doctor will need to rule out other conditions that can affect the foot, such as infection and stress fracture. You will be asked to provide detailed information about your general health, your family medical history (especially any previous tumors or cancers in a family member), your current symptoms, and the medications you’re taking.
The physical examination will focus on the type, size, location, and tenderness of the tumor, and on the range of motion of the foot. Your doctor may examine other parts of your body to determine whether they may also be affected. This is important when there is suspicion of bone cancer, which can metastasize. Malignant tumors can be misdiagnosed. You may want to get a second opinion to confirm a diagnosis of bone cancer.
You will most likely need to undergo some radiographic testing of the foot, which may include x-rays, computerized tomography, or magnetic resonance imaging. Occasionally, benign bone tumors may be discovered incidentally when radiographs are taken for other reasons, such as a sprained ankle. The radiographic findings will vary depending on the condition. In some cases, more invasive testing — for example, a biopsy — may be needed for diagnosis.
Bone Tumor of the Foot Treatment
Some benign bone tumors of the foot may not require treatment. For instance, a benign bone tumor that occurs in a child may resolve over time. Monitoring of the tumor may be all that is needed. Some people with bone tumors can be treated effectively with medication. Others, such as those with osteochondroma, may require surgery. Excision of the tumor often solves the problem, although bone tumors can recur.
For people with malignant bone tumors, treatment may involve several specialists and a combination of interventions, including radiation therapy, chemotherapy, and surgery. The surgeon will need to take out the tumor and some of the healthy tissue and bone around it. In some instances, the excised bone can be replaced with a metallic implant or bone transplant (this is known as limb salvage surgery). In cases of advanced bone cancer, amputation of the foot may be necessary.
After you have been treated for a bone tumor, you will have to return for follow-up and undergo more radiographic testing so your doctor can make sure that the treatment was successful and that the tumor has not recurred.