Fibrous dysplasia of bone is a condition in which the bone is replaced by fibrous tissue. It is considered to be a neoplasm though in true sense it is developmental abnormality of bone than a true neoplasm.

The disease may affect a single boneo one bone or may occur in many bones.

The condition begins in childhood and it may progress beyond puberty. Both males and females are equally affected.

Commonly affected  bones are long bones of lower extremities and base of skull.Pathological fractures are very common and heal rapidly but with deformity. The fractures are  microfractures and over the time  cause deformity. Bowing of the femoral shaft and varus deformity producing characteristic Shepherd’s crook deformity.

Shphered Crook Deformity and Pathological fracture In Fibrous Dysplasia of Femur

A hyperostosis at the base of skull can encroach on the sinuses and foramina.  Cranial lesions may cause progressive visual impairment or hearing loss.

Initially, the disease is asymptomatic. Usully the symptoms begin before beginning of second decade of life.

Initial complaint may be a limp, pain in the leg or fracture.

Laboratory studies ie serum calcium, phosphorus, and alkaline phosphatase levels are normal. Alkaline Phosphatase may be raised in severe cases.

Diagnosis is made by biopsy.

Xrays show lesion to have a lucent or “ground glass” appearance, cause thinning of the cortex and endosteal scalloping. Tiny purposeless trabeculae are noted within the lesion.

The lesion would produce a typical deformities depending on site of the lesion. These include

• Shepherd’s crook deformity of femur
• Intrapelvic protrusion of the acetabulum
• Harrison’s groove following rib fractures.

Thickening of base of  of skull is a feature of this disease.

When extensive fibrous dysplasia develops in early life, progression is marked with severe deformities and fractures.

However if it has only localized involvement is there, it has a favorable outlook.

Malignant change doesn’t occur generally. However it has been noted with irradiation.

Lesions of upper limb are generally not interfered with untill they threaten an impending fracture. Lower extremity lesions, especially involving the proximal femur, are particularly challenging and associated with significant morbidity.

Age of the patient plays a significant role in outcome.

Curettage and bone grafting appear to provide satisfactory results. Sometimes deformity correction and use  of internal fixation may be required in severe cases.

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