Pediatric Radiology > Musculoskeletal > Benign Lesions > Fibrous Dysplasia

Fibrous Dysplasia

Fibrous dysplasia is a developmental disorder in which medullary bone is replaced by fibrous tissue and abnormal bone. It typically occurs in children between the ages of 5 and 20 and is often associated with endocrine disorders like hyperthyroidism and hyperparathyroidism. This disorder is associated with a very low risk of malignant transformation.

There are two types of fibrous dysplasia:

  1. Monostotic fibrous dysplasia (85%) - predilection for ribs, femur and skull
  2. Polyostotic fibrous dysplasia (15%) - typically in younger children (mean age = 8 years); likely to involve pelvis with concurrent involvement of ipsilateral proximal femur; also found in proximal femur (without pelvic involvement) and in tibia.

McCune-Albright Syndrome - triad of features include:

  • polyostotic, usually unilateral, fibrous dysplasia
  • endocrine abnormalities (precocious puberty, hyperthyroidism)
  • cafe au lait spots


Fibrous Dysplasia of femoral metaphysis in an 8-year-old girl. A, AP view shows an expansile lesion in the metaphysis of the right femur. This lesion exhibits some scalloping of the intracortical margin with a ground-glass appearance. A pathologic fracture is seen across the distal femoral neck. B, CT through bilateral femurs shows thinning of the cortex and abnormal increased density within the medullary cavity. CT numbers measured 150 Hounsfield units in the right medullary cavity versus 23 (normal) on the left.
Polyostotic fibrous dysplasia in an 11-year-old female with precocious puberty (McCune-Albright syndrome). Plain film of left forearm shows a "ground glass" geographic lesion in the radius consistent with fibrous dysplasia. Note the healing pathologic fracture in the mid-shaft. A similar ground glass lesion was noted in the patient's left humerus, the distal aspect of which can be seen on this film.


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