A non-ossifying fibroma (NOF) is one of the most common bone tumors found in children between 8–20 years of age. They are non-cancerous (benign) and do not spread to other areas of the body. NOFs are commonly found in the flared end of thighbone (femur) or shinbones but can also occur in the bones of the upper arm or lower leg. They tend to persist or increase in size as the child grows. However, once the growth ends, they tend to decrease in size or close. The most common complication of a NOF is a fracture.
The cause of NOFs is unknown.
Most often, NOFs have no symptoms and are not discovered until they are detected by chance during an exam for another issue. If a child does experience symptoms, they can include:
NOFs are usually discovered when a child has an X-ray for reasons other than checking for NOF. If there was pain before the injury that seems to arise from the lesion, NOF is probably not the cause.
Most lesions do not require treatment and tend to heal spontaneously on their own as the child’s bones mature.
If there is a fracture, doctors will usually use a cast to immobilize the area. These fractures usually heal well, but the NOF may or may not get better.
Surgery is recommended for patients who do not properly heal with a cast, or are likely to re-break the bone if the lesion is large.
A NOF can weaken the bone where it occurs which puts your child at risk for repeated fractures. In these cases, surgery may be recommended to scrape the inside of the bone (curettage). A doctor may use donor bone or a bone graft substitute to fill in the area.