Pediatrics

Non-ossifying fibroma

introduction

The non-ossifying fibroma usually does not cause pain or other symptoms and is often radiographed random found.
It is one of the most common benign Changes in the bone and is almost always accompanied by spontaneous healing.

definition

The non-ossifying fibroma is not a real neoplasm, but a developmental malformation. Instead of a bone, connective tissue is built in at this point. The non-ossifying fibroma is therefore a disease in childhood and usually heals spontaneously by ossifying towards the end of growth. Sometimes a small residue remains in the bone area of the metaphysis or diaphysis. The metaphysis is the section of long tubular bone and the diaphysis is the area of the bone shaft.

Clinical signs of the non-ossifying fibroma

As I said, the non-ossifying fibroma is an incidental finding as it does not cause pain. It is often discovered in connection with a fall on the knee when an X-ray is taken to rule out a fracture.
Pain in the area of the fibroma is only very rarely expressed. Often it is knee pain, as the non-ossifying fibroma is mostly in this area. Such complaints are often a sign of a rapid spread of the benign change or an imminent pathological fracture.
Pathological fracture means that no external force has caused a break in the bone. In some cases there is a slight swelling of the soft tissue in the area of the shin bone.

Pain with a non-ossifying fibroma

In most cases, non-ossifying fibroids are completely symptom-free. However, if the skeleton is unstable, fractures can occur without an appropriate accident. Accordingly, this can be painful.
In some cases, the children suffer from disabilities and pain even without a fracture. If the symptoms persist, surgical therapy or splints can be considered.

Treatment of the non-ossifying fibroma

The non-ossifying fibroma shows a typical x-ray finding and usually heals spontaneously. If there is no additional pain, no further radiological follow-up is required.
If the lesion is larger than half the bone, if the pain is constant, and if the patient is young, a follow-up check should be performed two times a year respectively. In this way, a pathological break can be recognized and treated in good time. If this is the case, surgical intervention takes place. The non-ossifying fibroma is cleared out, i.e. a curettage is carried out. If the area of clearance is very large, the area can also be filled with cancellous bone, the spongy bone structure.

Which bones are often affected?

The non-ossifying fibroma is a bone formation disorder and therefore particularly affects bones that are growing rapidly. The long bones are most commonly affected. These include the bones of the upper and lower arms and the upper and lower legs.
Over ninety percent of the cases affect the lower extremities, i.e. the legs. With further growth, the ossification is usually made up for and no therapy has to be initiated.

Imaging of a non-ossifying fibroma

By a radiological imaging the non-ossifying fibroma can be detected as an incidental finding. Due to the classic appearance, the diagnosis can be made with great certainty and in only rare cases further imaging is initiated or a biopsy is suggested.
The lesion is usually found directly above the periosteum and is a hollow and thinning of the cortex (= compact bone layer located directly under the periosteum). In some places no cortex can be seen at all.
The boundary to the spongy interior of the bone, the cancellous bone, is smooth and sharp and is characterized by increased connective tissue. The non-ossifying fibroma shows up as irregularly large lobules that appear significantly darker in the X-ray than the healthy bone.

roentgen

In most cases, the non-ossifying fibroma does not cause any symptoms and is almost always an incidental finding in the X-ray image for other questions. In the X-ray the non-ossifying fibroma appears as a lightened area. It is a grape-shaped, lighter area, usually seen in the long tubular bones. The place is sharply delimited, which is a sign of its benignity. In the case of a known non-ossifying fibroma, regular x-ray examinations should take place in order to observe the regression during growth.

MRI

The MRI is a high-resolution possibility to evaluate different body structures. The advantage of MRI compared to conventional X-ray diagnostics is that there is no radiation exposure. A non-ossifying fibroma can also be an incidental diagnosis on MRI. In the case of a known non-ossifying fibroma, regular checks are necessary, but these are always associated with radiation exposure. This can be prevented with MRI controls. MRI examinations are significantly more expensive than conventional X-rays and are therefore only approved by health insurance companies in exceptional cases.

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Differential diagnosis

The non-ossifying fibroma shows a clear picture on X-rays and does not actually require any further diagnostics. Other clinical pictures can almost always be differentiated from a non-ossifying fibroma by their radiological picture.
The aneurysmal 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 picture is chondromyxoid fibroma. It is also located in the metaphysis of the knee region. Clinically, it can be clearly delineated by its pain intervals. If you are still unsure, an MRI can be performed.

Find out more about the here aneurysmal bone cyst

Frequency of the non-ossifying fibroma

As already mentioned, the non-ossifying fibroma is the most common benign (benign) Bone changes. Exact numbers cannot be given due to the chance finding. It is known that the majority of it is diagnosed between the ages of 10 and 15. Boys and girls are equally often affected.
The non-ossifying fibroma occurs almost exclusively on the lower extremities, and it is almost always found in the metaphysis of the femur near the knee. If it does not appear there, it can usually be found in the shin metaphysis near the foot or near the knee. Often times are based on an incidental finding several diagnosed non-ossifying fibroids.

Course of disease

The non-ossifying fibroma usually heals spontaneously. There are no known malignancies in these bone changes. There are three phases of the non-ossifying fibroma.
In the active phase the non-ossifying fibroma is on the metaphyseal side of the Growth plate. Due to the constant growth, it migrates in the direction of the metaphyseal and diaphyseal area. Additionally grow Bone bridges into the connective tissue structure.
Then follows the quiet phase. It is characterized by the transformation of the bone around the lesion and the thickening of the connective tissue (sclerosing) bone edge. The compact bone layer partially thins so that it is no longer visible in the X-ray. At the end of the growth phase, the non-ossifying fibroma lies in the transition area between the meta- and diaphysis.
The last phase is the latent phase. Here it comes to Healing and restoration of the bone. In a few cases, however, tears in the fibroma or a break can occur, which can heal normally.

Conclusion

The non-ossifying fibroma is in most cases an incidental radiological finding and occurs mainly in children and adolescents. It is about a benign Connective tissue bone change, which in most cases heals spontaneously.
Very rarely can it become one fracture come, which also heals on its own. If the area of the non-ossifying fibroma is very large, it is recommended to remove it and fill it with cancellous bone.
Actually there are no real differential diagnoses, i.e. other diseases that resemble the picture of the non-ossifying fibroma. If you are still not sure, an MRI can serve as further protection.