Differential diagnosis

The non-ossifying fibroma shows a clear image on X-ray and does not actually require any further diagnosis. Other clinical pictures can almost always be distinguished from non-ossifying fibroma by their radiological image. For example, the aneurysmatic bone cyst shows a fluid level in the MRI and affects the entire transverse area of the bone.

A giant cell tumor is located in a different area of bone than the non-ossifying fibroma. The only clinical picture that really resembles a non-ossifying fibroma in the radiological image is chondromyxoidal fibroma. It is also found in the metaphysis of the knee region. Clinically, it can be clearly defined by its pain intervals. If you are still not sure, an MRI can be performed.

Frequency of non-ossifying fibroma

As already mentioned, non-ossifying fibroma is the most common benign bone alteration. Exact numbers cannot be given because of the random findings. It is known that it is mostly detected between the ages of 10 and 15 years.

Boys and girls are equally affected. The non-ossifying fibroma occurs almost exclusively in the lower extremities and is almost always found in the area of the metaphysis of the femur near the knee. If it does not occur there, it is usually found in the shin metaphysis near the foot or near the knee. Often several non-ossifying fibromas are diagnosed after a random finding.

Course of disease

The non-ossifying fibroma usually heals spontaneously. Malignant degenerations are not known in these bone changes. There are three phases of non-ossifying fibroma.

In the active phase, the non-ossifying fibroma is located on the metaphyseal side of the growth plate. Due to the steady growth, it migrates towards the metaphyseal and diaphyseal regions. In addition, bone bridges grow into the connective tissue structure.

This is followed by the quiet phase. Characteristic is the transformation of the bone around the lesion and the thickening of the connective tissue (sclerosing) bone margin. In some cases, the compact bone layer thins, so that it is no longer visible in X-rays.

At the end of the growth phase, the non-ossifying fibroma is located in the transitional area of the metaphysis and diaphysis. The last phase is the latent phase. This is when the bone heals and is restored. In a few cases, however, there may be tears in the fibroma or a fracture, but this can heal normally.