It is possible that bone cancer may cause a lump on the foot, although this is rare. It is more common for a tumor in the foot to be benign.

Cancer can develop when cells in the body start to grow out of control. Bone cancer is a malignant tumor that originates in the cells of the bone. It can cause pain, swelling, redness, and a noticeable lump.

There are three main types of bone cancer in the foot, including osteosarcoma, chondrosarcoma, and Ewing sarcoma. Bone cancer is rare and accounts for approximately 0.5% of cancers in the United States. More often, however, foot tumors are benign, with 30% of all foot tumors typically being synovial cysts.

In this article, we will discuss whether bone cancer can cause a lump on the foot, the treatment options available, and potential other causes.

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One possible cause of a lump on the foot is bone cancer. However, malignant tumors only account for approximately 15–25% of tumors in the foot.

Bone cancer can form in any bone in the foot, including the bone marrow.

Studies suggest that the most common place a malignant tumor in the bones of the foot may form is in the metatarsal bones. The second most common place is in the big toe. The third most common is in the rear of the foot, and the fourth most common is in the arch of the foot.

Learn more about bone cancer here.

Aside from causing a lump on the foot, bone cancer in the feet can present several other symptoms, including:

  • continual pain in a bone of the foot that worsens over time, particularly if near the ankle joint
  • weakness in the bones of the feet that can lead to fractures
  • inflammation of a bone in the foot that can restrict movement
  • unexpected weight loss, although this is less common
  • excessive sweating, particularly at night, although this is less common
  • fever, although this is less common

If a person develops a lump on the foot, a doctor may enquire if there is any pain in the foot, whether the pain is constant or fluctuates, if anything makes the pain worse, or if there is any difficulty moving the foot. A doctor may then examine the lump.

Following examination, a doctor may recommend further tests. These can include:

  • X-ray: This procedure can detect any damage to the bones or any new bone that is growing in the foot due to bone cancer.
  • Biopsy: This procedure can determine if bone cancer is present, what type of bone cancer it is, and how serious it is. A biopsy is the most conclusive way to diagnose bone cancer in the foot. A surgeon may perform a core needle biopsy using a thin needle to remove a tissue sample or an open biopsy, cutting a sample of tissue from the affected bone.
  • MRI scan: This procedure can be useful for defining the size of any tumors in the foot and whether the cancer has spread.
  • CT scan: A doctor may recommend this procedure to determine if the bone cancer in the foot has spread to the lungs.
  • Bone marrow biopsy: A doctor may perform this procedure using a needle to extract a tissue sample to determine if the bone cancer has spread to the bone marrow in the foot.

Treating bone cancer in the foot can be complex. The type of treatment a person receives may depend on several factors. These can include the type of bone cancer, the extent of the cancer, which part of the foot the cancer originated in, and the general health and well-being of a person.

Some of the treatment options available for bone cancer in the foot include:

  • Surgery: There are two types of surgery a person may undergo for bone cancer in the foot. Limb salvage surgery, which removes the cancer and a small amount of surrounding tissue but keeps the foot intact, or amputation, which removes the cancer and all or part of the foot.
  • Radiation therapy: This uses high doses of radiation to kill bone cancer cells and reduce the size of tumors in the foot.
  • Chemotherapy: Uses anticancer medications to destroy bone cancer cells in the feet.
  • Targeted medications: Kinase inhibitors can treat bone cancer in the feet by stopping or slowing the growth of tumors. Immunotherapy drugs can help the immune system recognize and attack bone cancer cells in the feet.

There are several possible causes of a lump on the foot that do not have a link with bone cancer. Some of these include:

  • Bunions: Bunions appear when the big toe starts leaning inwards, causing a lump on the joint at the bottom of the big toe.
  • Accessory navicular syndrome: This is an extra bone on the inside of the foot that can cause a painful lump.
  • Haglund’s deformity: A bony lump on the back of the heel.
  • Ganglion cysts: These are fluid-filled swellings that can appear near a joint or tendon in the foot.
  • Bursitis: A bursa is a fluid-filled sac that acts as a cushion between the bones and tendons in the feet. Bursitis can occur when the bursa becomes inflamed.
  • Plantar fibromas: These are lumps on the plantar fascia, which runs from the heel bone to the base of the toes.
  • Lipomas: These are benign tumors in the feet that can occur when there is an overgrowth of fat cells.
  • Giant cell tumors: These are rare, benign tumors in the feet that can have the tendency to grow aggressively.

Bone cancer is a rare form of cancer that accounts for less than 1 in 100 cancers in the U.S. Bone cancer can be the cause of a lump on the foot, although this is not common.

Several conditions, including bunions, benign tumors, and bursitis, can also be the cause of a lump on the foot.

A doctor will need to carry out a full examination and may conduct several tests, including a biopsy, to diagnose bone cancer in the foot.

If a person receives a diagnosis of bone cancer in the foot, there are several treatment options available, including surgery, radiation therapy, chemotherapy, and targeted medications.