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What is a non-ossifying fibroma?

A non-ossifying fibroma is a benign (non-cancerous) bone tumor composed mainly of fibrous tissue.

Non-ossifying fibromas are the most common type of benign bone tumor: Between 20 to 40 percent of children, mainly between 10 and 15 years old, have a non-ossifying fibroma.

Most non-ossifying fibromas occur near the knee in the femur (thighbone) or tibia (shinbone), but may also occur in the humerus (upper arm bone). While these tumors sometimes occur in groups of two or three, most patients have only one non-ossifying fibroma.

Non-ossifying fibromas:

  • Are usually not painful or symptomatic
  • Are not cancerous and not aggressive (don’t spread)
  • Usually go away on their own after a child’s bones have stopped growing

Non-Ossifying Fibroma | Symptoms & Causes

What are the symptoms of a non-ossifying fibroma?

Most non-ossifying fibromas produce no symptoms at all. In fact, many are discovered by chance on an X-ray taken for a different reason.

If your child does have symptoms, they may experience:

  • Swelling or tenderness in the affected area
  • Dull pain in the affected bone that can get worse with activity
  • Pain with activity: usually the sign of a large tumor causing a structural weakness in the bone

What causes a non-ossifying fibroma?

Non-ossifying fibromas occur for no known reason.

Teen boy travels on surfboard in body of water

Adam takes a pause from his active life for non-ossifying fibroma

When a bump on his shin turned out to be a very large bone tumor, this active tween from Maine had to slow down for a summer.

Non-Ossifying Fibroma | Diagnosis & Treatments

How are non-ossifying fibromas diagnosed?

Your child’s doctor will take a full medical history and examine your child’s leg (or arm if the tumor is located there).

  • An X-ray will allow your child’s doctor to see the size and location of the tumor.
  • If the tumor is large, your child’s doctor may order a CT scan or MRI, which helps them look for signs that the surrounding bone has become thin or weak.

How are non-ossifying fibromas treated?

Most non-ossifying fibromas go away on their own without treatment. Your child’s doctor may recommend regular follow-up visits so they can observe the tumor over time to see if it changes in size.

In the rare case that a non-ossifying fibroma becomes painful, weakens the bone, or leads to fracture, your child’s doctor will recommend surgery to remove it.

Surgery to remove a large non-ossifying fibroma is called curettage. For this simple procedure, an orthopedic surgeon will use a tool called a curette to scrape the tumor out of the bone. They will then pack the cavity with bone material, which may come from a donor or from another part of your child’s body, to stimulate new bone growth. Bone from a donor is called an allograft, while bone from a patient’s own body is called an autograft.

What is the long-term outlook for a child with a non-ossifying fibroma?

The long-term outlook for children with non-ossifying fibromas is good. Most of these tumors heal spontaneously by the time the bone has finished growing.

Most children who have surgery to remove non-ossifying fibromas are able to return to full activity within three to six months.

Whether or not your child has surgery, it’s important they see their doctor for regular follow-up visits to monitor the health of their affected bone.

How we care for bone tumors and bone cysts

The pediatric orthopedic surgeons in the Bone and Soft Tissue Tumors Program at Boston Children’s Hospital are nationally recognized for their expertise in caring for children with bone tumors, bone cysts, and soft tissue tumors. We take a multidisciplinary approach to ensuring that every one of our patients receives personalized, supportive care before, during, and after their treatment.

Non-Ossifying Fibroma | Programs & Services

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