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​Fibrous Dysplasia

Fibrous dysplasia is a rare, benign bone disease. It occurs when abnormal fibrous, scar-like tissue replaces healthy bone.

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What Is Fibrous Dysplasia?

Fibrous dysplasia is a rare bone disorder. Abnormal, weak bone forms in place of normal bone tissue, thereby weakening the bone.

The disease starts early in life. Though it doesn't spread beyond the original scope of affected bones, it's irreversible.

The most common bones affected by this disease are:

  • Skull and facial bones.
  • Thighbone.
  • Shinbone.
  • Pelvic bones.
  • Ribs.
  • Upper arm bone.

Types of fibrosis dysplasia include:

  • Monostotic fibrous dysplasia affects only one bone.
  • Polyostotic fibrosis dysplasia affects more than one bone.

Monostotic vs. polyostotic fibrosis dysplasia

In most people, fibrous dysplasia affects only one bone (monostotic).

Polyostotic makes up about 20 to 30 percent of cases.

The polyostotic form often becomes apparent before age 10, whereas detecting the monostotic form depends on the affected bone.

Fibrous Dysplasia Symptoms and Diagnosis

Symptoms of fibrous dysplasia may include:

  • Head or facial deformities.
  • Bone pain.
  • Swelling.

Other symptoms may include light brown birth marks café-au-lait spots) and endocrine dysfunctions such as:

  • Premature puberty.
  • Hyperthyroidism.
  • Excessive production of growth hormone.

These are signals of a condition called McCune-Albright syndrome, of which polyostotic fibrous dysplasia is one manifestation.

To help diagnose fibrous dysplasia your doctor will:

  • Perform a physical exam.
  • Ask you about your symptoms.
  • Order imaging and other diagnostic tests.

Tests for diagnosing fibrous dysplasia

Images provided by x-rays, MRI, and CT scans can reveal the presence and extent of abnormal tissue in the affected bones.

Your doctor may also order a bone scan.

In cases of polyostotic fibrous dysplasia, you may also need blood tests to assess endocrine function.

If your doctor suspects cancer — which is rare — they may order a biopsy. In severe cases of fibrous dysplasia, the bone lesions can become cancerous.

Fibrous Dysplasia Treatment

Surgery may be necessary for more problematic cases of fibrous dysplasia involving chronic pain, fractures, or deformity.

Surgical treatment for fibrous dysplasia involves partial removal of the affected bone. Surgeons may also insert stabilizing agents such as metal plates, rods, and screws.

Minimally invasive surgery for fibrous dysplasia of the skull base

At UPMC, the preferred surgical treatment for fibrous dysplasia of the skull base is the Endoscopic Endonasal Approach (EEA)

Although fibrous dysplasia is irreversible, this state-of-the-art, minimally invasive treatment allows surgeons to:

  • Access fibrous dysplasias through the natural corridor of the nose, without making an open incision.
  • Remove the affected bone causing symptoms through the nose and nasal cavities.

Benefits of EEA include:

  • No incisions to heal.
  • No disfigurement.
  • Faster recovery time.

To preserve sight, surgeons will perform optic nerve decompression in cases where fibrous dysplasia causes compression of the optic canal.

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