Fibrous Dysplasia

Generality

Fibrous dysplasia is a benign tumor that affects the bones and induces, in the latter, the replacement of normal bone with fibrous (or scar tissue).

Image from the site orthoinfo.aaos.org

It is a congenital disease due to a genetic mutation taking place after conception, precisely during the early stages of fetal development.

Typical clinical manifestations are: pain, tendency to fractures, bone deformities and episodes of nerve compression.

Fibrous dysplasia mainly affects the bones of the skull and the long bones of the arms and legs.

There is no specific cure for fibrous dysplasia, but only symptomatic treatment.

Short review of what a tumor is

In medicine, the terms tumor and neoplasia identify a mass of very active cells, able to divide and grow uncontrollably.

We speak of a benign tumor when the growth of cell mass is not infiltrative (that is, it does not invade the surrounding tissues) and even metastasizing.
There is talk of a malignant tumor when the abnormal cell mass has the ability to grow very quickly and to spread to the surrounding tissues and the rest of the body.
The terms malignant tumor, cancer and malignant neoplasia are to be considered synonymous.

What is fibrous dysplasia?

Fibrous dysplasia is a benign-type bone tumor characterized by the replacement of normal bone tissue with fibrous tissue .

Therefore, in those suffering from fibrous dysplasia, the bone or bones affected by the neoplasm change their cellular composition, losing the normal cellular component in favor of a fibrous component, which, under physiological conditions, would be completely absent.

The skeletal districts most affected by fibrous dysplasia are the bones of the skull and the long bones of the legs and arms .

WHAT IS FIBROUS FABRIC?

Fibrous tissue is a non-functional tissue composed of a cluster of collagen fibers. Its formation is due to a hyperactivity of some particular cells, belonging to the connective tissue and known as fibroblasts .

The fibrous tissue is also called scar tissue .

TYPES OF FIBROUS DISPLASIA

Pathologists recognize the existence of two types of fibrous dysplasia: monostotic fibrous dysplasia and polyostotic fibrous dysplasia .

Monostotic fibrous dysplasia affects only a bone of the human skeleton and represents the most common type of fibrous dysplasia.
Polyostotic fibrous dysplasia affects more bones than the human skeleton. The affected bones can all belong to the same limb or to different limbs.

Among the two types of fibrous dysplasia, the most serious from a medical-clinical point of view is polyostotic fibrous dysplasia.

Epidemiology

Fibrous dysplasia is a condition that mainly affects adolescents and so-called young adults: in support of what has just been stated, a statistical survey has shown that just under 75% of people with fibrous dysplasia are less than 30 years old.

Causes

Fibrous dysplasia occurs due to a genetic mutation of DNA, which, at the skeletal level, alters the production and differentiation of the cells making up the bone tissue.

The aforementioned genetic mutation is the event that fibrous tissue is formed instead of normal bone tissue.

WHAT IS THE GENE INVOLVED?

The genetic mutation that causes fibrous dysplasia affects the GNAS gene . The GNAS gene encodes the homonymous GNAS protein, which plays a fundamental role during the processes of production and differentiation of the cells making up the bone tissue.

WHEN IS THE MUTATION PLACE?

Fibrous dysplasia is a congenital disease - that is, present from birth - but not hereditary - that is, it is not transmitted by either parent.

This means that the mutation that the cause takes place during fetal development, then after conception and when the future sick subject is still in the maternal uterus.

Scientific studies have shown that the mutation responsible for fibrous dysplasia takes place during the early stages of fetal development.

Symptoms and Complications

Mild forms of fibrous dysplasia do not cause any particular symptoms or signs; the serious forms, instead, are generally responsible for:

Bone pain
Bone deformities;
Fractures against the affected bone or bones;
Episodes of nerve compression.

ASSOCIATIONS

Typically, fibrous dysplasia arises as a solitary condition.

However, in some rare situations, for reasons not yet completely clear, it appears in association with:

McCune-Albright syndrome ;
Some diseases of the endocrine system, including: hyperthyroidism, hyperparathyroidism, acromegaly, diabetes mellitus and Cushing's syndrome;
Mazabraud's syndrome .

WHEN TO REFER TO THE DOCTOR?

A pain in the bones - like the one that can derive from fibrous dysplasia - is to be put to the attention of doctors when:

Increases during running, walking, jumping etc;
It is disturbing sleep at night;
Does not improve with rest;
It causes lameness (if, of course, the pain concerns one of the two lower limbs).

COMPLICATIONS

Severe forms of fibrous dysplasia can be the cause of various complications, including:

Continuous severe fractures and deformities of the bone or bone affected by the tumor.
Reduced vision / loss and hearing loss / loss. These are two typical complications of severe episodes of fibrous dysplasia located in the bones of the skull.
Their onset can have two causes: it may be due to compression, on the part of the tumor mass, of the optical and acoustic nerves or it may be due to bone deformities, consequent to the neoplasm, which modify the anatomy of the organs of sight and hearing .
Arthritis. It is a typical complication of severe episodes of fibrous dysplasia located near the knee joints, elbow joints etc.
The appearance of arthritis causes bone deformities, which derive from the neoplasm.
Change in malignant tumor. Although this is a very remote possibility, fibrous dysplasia can assume the characteristics of a malignant bone tumor.

Diagnosis

For an accurate diagnosis of fibrous dysplasia, the following are fundamental: physical examination, anamnesis, diagnostic imaging tests (eg X-rays, nuclear magnetic resonance, CT, bone scintigraphy, etc.) and tumor biopsy.

DIAGNOSIS OF ASINTOMATIC CASES

In general, the detection of mild cases of fibrous dysplasia occurs in a completely random manner, for example during X-ray examinations performed for other reasons.

Treatment

Being a genetic disease, fibrous dysplasia is a condition from which it is impossible to heal.

All this, however, has not prevented doctors from developing treatments capable of reducing the symptoms and the likelihood of complications.

TREATMENTS IN CASE OF FIBROY DISPLASIA LIEVE

Generally, fibrous dysplasia in mild form does not require any treatment, as - as stated on several occasions - it is an asymptomatic condition and, more often than not, goes unnoticed.

The only recommendation by doctors to patients with mild fibrous dysplasia is to undergo periodic X-ray examinations, to keep the neoplastic condition under control and to be aware of any changes in the latter.

TREATMENTS IN CASE OF SERIOUS FIBROUS DISPLASIA

The treatments envisaged for severe fibrous dysplasia include:

The administration of some drugs for osteoporosis, in particular pamidronate (a bisphosphonate). These medicines are not specific for fibrous dysplasia, but by strengthening the bones, they seem to protect the latter from fractures and deformities;
The use of a protective brace, to be applied to the bone or bones affected by the tumor, to prevent fractures and limit the progression of deformities;
A series of surgical procedures for:

Correct deformities;
Fix the fracture or fractures;
Remove the bony sections affected by the tumor, to reduce fracture episodes and pain. In these situations, a bone transplant is also planned;
Decompress optic and acoustic nerves when fibrous dysplasia is located at the level of the skull bones.

SOME MEDICAL ADVICE

In the opinion of the doctors, the patients - especially the younger ones - are better able to accept the condition of patients with fibrous dysplasia, if they learn everything about it and attend a support group for people with the same genetic pathology.

Prognosis

The prognosis in case of fibrous dysplasia depends on the presence or absence of symptoms.

Although it is a permanent condition, mild fibrous dysplasia is a condition with which it is possible to coexist and which does not affect the quality of life of those affected.

On the other hand, the case of severe forms of fibrous dysplasia is different: these, in fact, often lead to complications and prevent the sick from leading a normal life.