Fibrous Dysplasia: Symptoms, Causes, Treatment

What are the symptoms of fibrous dysplasia?

Fibrous dysplasia is a rare bone disorder where normal bone and marrow are replaced with fibrous tissue, leading to weak bones, fractures, and deformities. The symptoms can vary depending on the severity and location of the affected bones. Common symptoms include:

1. Bone Pain: Persistent or intermittent pain in the affected bones, often worsening with physical activity.
2. Fractures: Bones that are weakened by the fibrous tissue are more prone to fractures.
3. Bone Deformities: Abnormal growth or curvature of the affected bones, which may lead to visible deformities.
4. Limb Discrepancy: One limb may be longer or shorter than the other due to uneven bone growth.
5. Swelling or Bumps: Noticeable lumps or swelling over the affected bones.
6. Functional Impairment: Reduced mobility or difficulty using the affected limb or area.
7. Nerve Compression: If the fibrous tissue presses on nerves, it can cause numbness, tingling, or weakness in the affected area.
8. Hearing or Vision Problems: If the bones of the skull or face are affected, it can impact hearing or vision.
9. Endocrine Issues: In some cases, hormonal imbalances can occur, leading to early puberty or other endocrine abnormalities (associated with McCune-Albright syndrome).

What are the causes of fibrous dysplasia?

Fibrous dysplasia is caused by a genetic mutation in the GNAS gene, which affects the cells that produce bone. This mutation occurs after conception (somatic mutation), meaning it is not inherited from parents and is not passed on to children. Here are the main points regarding the cause of fibrous dysplasia:

1. GNAS Gene Mutation: The mutation in the GNAS gene leads to the production of an abnormal protein that disrupts the normal development and maintenance of bone. This causes normal bone to be replaced with fibrous tissue, resulting in weak and deformed bones.
2. Somatic Mutation: The mutation occurs in the cells of the developing embryo after conception. Therefore, it is present in some but not all of the body’s cells, leading to the patchy distribution of affected bone areas.
3. Mosaic Distribution: Because the mutation occurs after conception, fibrous dysplasia often affects only specific bones or regions of the body rather than being widespread. This mosaic distribution can result in varying severity and symptoms.
4. McCune-Albright Syndrome: In some cases, the GNAS mutation is associated with McCune-Albright syndrome, a condition that includes fibrous dysplasia, café-au-lait spots (pigmented skin patches), and endocrine abnormalities (such as early puberty).

The exact reason why the GNAS mutation occurs is not well understood, but it is not caused by environmental factors or lifestyle choices. Research is ongoing to better understand the mechanisms behind this mutation and its effects on bone development.

How is the diagnosis of fibrous dysplasia made?

The diagnosis of fibrous dysplasia, also known as McCune-Albright syndrome, is typically made through a combination of medical history, physical examination, laboratory tests, and imaging studies. Here are the steps involved in diagnosing fibrous dysplasia:

1. Medical history: A thorough medical history is taken to identify any symptoms, such as pain, swelling, or deformity in the affected bone or joint.
2. Physical examination: A physical examination is performed to assess the affected bone or joint and look for any signs of deformity, swelling, or limited mobility.
3. Laboratory tests:
   • Complete blood count (CBC) and blood chemistry tests are done to rule out other conditions that may cause similar symptoms.
   • Serum calcium levels are measured to check for hypercalcemia (elevated calcium levels), which is a common finding in fibrous dysplasia.
   • Hormone levels, such as cortisol and thyroid-stimulating hormone (TSH), may be measured to evaluate for possible endocrine disorders.
4. Imaging studies:
   • X-rays: A radiograph (X-ray) of the affected bone is taken to visualize the bone density and architecture. Fibrous dysplasia appears as a radiolucent area (a dark spot) within the bone.
   • Computed tomography (CT) scan: A CT scan provides more detailed images of the affected bone and surrounding tissues.
   • Magnetic resonance imaging (MRI): An MRI may be used to evaluate the extent of bone involvement and assess for any soft tissue changes.
5. Biopsy: In some cases, a biopsy may be performed to confirm the diagnosis. This involves removing a small sample of bone tissue from the affected area and examining it under a microscope.
6. Genetic testing: In some cases, genetic testing may be done to identify mutations in the GNAS1 gene, which can help confirm the diagnosis of McCune-Albright syndrome.

The diagnosis of fibrous dysplasia is often made by a multidisciplinary team of healthcare professionals, including endocrinologists, orthopedic surgeons, radiologists, and geneticists.

What is the treatment for fibrous dysplasia?

The treatment for fibrous dysplasia typically depends on the symptoms and severity of the condition. Here are some common approaches:

1. Monitoring: In cases where the fibrous dysplasia is mild and not causing any significant symptoms, regular monitoring by a healthcare professional may be sufficient. This involves periodic check-ups to monitor the condition’s progression.
2. Medications: Pain management medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to alleviate any discomfort or pain associated with fibrous dysplasia.
3. Surgery: Surgery may be recommended for more severe cases of fibrous dysplasia or if the condition is causing complications such as bone deformity, fractures, or nerve compression. Surgical options may include bone grafting, osteotomy (surgical cutting of bone), or removal of the affected bone tissue.
4. Bisphosphonate Therapy: Bisphosphonates are medications that can help slow down the progression of fibrous dysplasia by reducing bone turnover. They are often used in combination with other treatments and may help relieve pain and stabilize bone lesions.
5. Hormonal Therapy: In some cases, hormonal therapy may be considered to help manage symptoms or slow down the progression of fibrous dysplasia, particularly in cases where the condition is associated with certain hormone-related disorders.
6. Physical Therapy: Physical therapy may be recommended to help improve strength, flexibility, and range of motion, especially if the fibrous dysplasia has resulted in bone deformities or functional limitations.

Treatment plans are typically tailored to the individual patient’s needs and may involve a multidisciplinary approach involving specialists such as orthopedic surgeons, endocrinologists, and pain management specialists. It’s essential for individuals with fibrous dysplasia to work closely with their healthcare team to develop an appropriate treatment plan based on their specific circumstances.

What age does fibrous dysplasia start?

Fibrous dysplasia typically starts in childhood or adolescence. The condition usually becomes apparent during the growth years, often before the age of 10. It can be present at birth, but symptoms and bone changes might not be noticeable until later in childhood or early adulthood. The extent and severity of the disease can vary widely among individuals. Early diagnosis and management are important to address symptoms and prevent complications.

What is the life expectancy for fibrous dysplasia?

Fibrous dysplasia is a benign bone disorder that affects the growth and development of bones. The life expectancy for individuals with fibrous dysplasia is generally normal, and most people with the condition can lead active and healthy lives.

However, the extent to which fibrous dysplasia affects quality of life and overall health can vary depending on several factors, including:

1. Location: Fibrous dysplasia can occur in various parts of the body, such as the arms, legs, or pelvis. The location of the affected bone can impact the severity of symptoms and the likelihood of complications.
2. Severity: The extent to which the bone is affected by fibrous dysplasia can also impact quality of life. In some cases, the condition may cause significant pain, limited mobility, or deformity, which can affect daily activities and overall well-being.
3. Complications: Fibrous dysplasia can lead to various complications, such as bone fractures, osteoarthritis, or sarcomatous transformation (a rare but potentially serious complication that involves the development of a cancerous tumor). The risk of these complications can impact life expectancy and overall health.
4. Treatment: The effectiveness of treatment can also impact quality of life and life expectancy. Treatment options for fibrous dysplasia may include medication, physical therapy, and surgery, which can help manage symptoms and prevent complications.

On average, people with fibrous dysplasia can expect to live a normal lifespan, with a life expectancy similar to that of the general population. However, it’s essential to work closely with a healthcare provider to manage symptoms and prevent complications to ensure optimal health and quality of life.

It’s also important to note that fibrous dysplasia is typically diagnosed in children or young adults, and in some cases, it may not be diagnosed until later in life. In these situations, the condition may have been present for many years before diagnosis, which can impact quality of life and overall health.