When cells divide abnormally and uncontrollably, they can form a mass or lump of tissue. This lump is called a tumor. Bone tumors form in your bones. As the tumor grows, abnormal tissue can displace healthy tissue. Tumors can either be benign or malignant. Benign tumors aren not cancerous. While benign bone tumors typically stay in place and are unlikely to be fatal, they are still abnormal cells and may require treatment. Benign tumors can grow and could compress your healthy bone tissue and cause future issues. Malignant tumors are cancerous. Malignant bone tumors can cause cancer to spread throughout the body.
Types of benign bone tumors

1. Osteochondromas: Benign tumors are more common than malignant ones. According to the American Academy of Orthopaedic Surgeons (AAOS), the most common type of benign bone tumor is an osteochondroma. This type accounts for between 35 and 40 percent of all benign bone tumors. Osteochondromas develop in adolescents and teenagers. These tumors form near the actively growing ends of long bones, such as arm or leg bones. Specifically, these tumors tend to affect the lower end of the thighbone (femur), the upper end of the lower leg bone (tibia), and the upper end of the upper arm bone (humerus). These tumors are made of bone and cartilage. Osteochondromas have been considered to be an abnormality of growth. A child may develop a single osteochondroma or many of them.
2. Nonossifying fibroma unicameral: Nonossifying fibroma unicameral is a simple solitary bone cyst. It is the only true cyst of bone. It is usually found in the leg and occurs most often in children and adolescents.
3. Giant cell tumors Giant cell tumors grow aggressively. They occur in adults. They are found in the rounded end of the bone and not in the growth plate. These are very rare tumors.
4. Enchondroma An enchondroma is a cartilage cyst that grows inside the bone marrow. When they occur, they begin in children and persist as adults. They tend to be part of syndromes called Ollier and Mafucci syndrome. Enchondromas occur in the hands and feet as well as the long bones of the arm and thigh.
5. Fibrous dysplasia Fibrous dysplasia is a gene mutation that makes bones fibrous and vulnerable to fracture.
6. Aneurysmal bone cyst An aneurysmal bone cyst is an abnormality of blood vessels that begins in the bone marrow. It can grow rapidly and can be particularly destructive because it affects growth plates.

What are the causes of bone tumors?
The causes of bone tumors are not known. A few possible causes are genetics, radiation treatment, and injuries to the bones. Osteosarcoma has been linked to radiation treatment (particularly high doses of radiation) and other anticancer drugs, especially in children. However, a direct cause has not been identified.
The tumors often occur when parts of the body are growing rapidly. People who have had bone fractures repaired with metal implants are also more likely to develop osteosarcoma later.
Recognizing potential symptoms of bone tumors
A dull ache in the affected bone is the most common symptom of bone cancer. The pain starts off as occasional and then becomes severe and constant. The pain may be severe enough to wake you up in the night.

1. Sometimes, when people have an undiscovered bone tumor, what seems like an insignificant injury breaks the already weakened bone, leading to severe pain. This is known as a pathologic fracture. Sometimes there may be swelling at the site of the tumor.
2. Or you might not have any pain, but you will notice a new mass of tissue on some part of your body. Tumors can also cause night sweats, fevers, or both.
3. People with benign tumors might not have any symptoms. The tumor might not be detected until an imaging scan reveals it while receiving other medical testing.
4. A benign bone tumor, such as an osteochondroma, may not require treatment unless it starts to interfere with your day to day function and movement.

Diagnosing a bone tumor
Fractures, infections, and other conditions might resemble tumors. To be sure you have a bone tumor, your doctor might order a variety of tests.

1. 1. .First, your doctor will do a physical exam with a focus on the area of your suspected tumor. They will check for tenderness in your bone and test your range of motion. Your doctor will also ask you questions about your family medical history.
   2. Blood and urine tests Your doctor may order tests, including blood or urine samples. A lab will analyze these fluids to detect different proteins that may indicate the presence of a tumor or other medical problems.
      An alkaline phosphatase test is one common tool doctors use to diagnose bone tumors. When your bone tissue is especially active in forming cells, large quantities of this enzyme show up in your blood. This could be because a bone is growing, such as in young people, or it could mean a tumor is producing abnormal bone tissue. This test is more reliable in people who have stopped growing.
   3. Imaging tests Your doctor will probably order X-rays to determine the size and exact location of the tumor. Depending on the X-ray results, these other imaging tests may be necessary:
      A CT scan is a series of detailed X-rays of the inside of your body that are taken from several angles.
      An MRI scan uses magnets and radio waves to provide detailed pictures of the area in question.
      In a positron emission tomography (PET) scan, your doctor will inject a small amount of radioactive sugar into your vein. Since cancer cells use more glucose than regular cells, this activity helps your doctor locate the site of the tumor.
   . An arteriogram is an X-ray of your arteries and veins.

1. . A bone scan may also be needed here is how they are done and what the results mean.

1. Biopsies Your doctor may want to perform a biopsy. In this test, a sample of the tissue that makes up your tumor will be removed. The sample is examined in a laboratory under a microscope. The main types of biopsies are a needle biopsy and an incisional biopsy.
   A needle biopsy may be done in your doctor office or by a radiologist along with one of the previously mentioned imaging tests. Either way, you will have local anesthetic to block the pain.
   Your doctor will insert a needle into your bone, using it to remove a small bit of tumor tissue. If a radiologist does the needle biopsy, they will use the image from the X-ray, MRI, or CT scan to help find the tumor and know where to insert the needle.
   An incisional biopsy, also called an open biopsy, is done in an operating room under general anesthesia so you will sleep through the procedure. Your doctor will make an incision and remove your tissue through the incision.
   Completing a bone biopsy is important to make a definite diagnosis of the condition.