Non-ossifying fibroma

The non-ossifying fibroma is a very common benign condition of the bone that presents in the teen years and is usually picked up incidentally. It has a bland appearance with sclerotic margins and is usually asmptomatic.They usually occur at the point of long bones where tendons attach to bone. Occasionally they may be so big as to confuse the diagnosis with something malignant. There is usually no reason to remove these lesions unless they are active on bone scan so as to be mistaken for a malignant bone tumor. Occasionally they may be big enough to cause pain due to a stress fracture as they weaken the bone especially around the hip.

Figure. This child had a right distal femur tumor. This was characteristic of non-ossifying fibroma but due to the size needed to be curretted and cemented.