Polyostotic fibrous dysplasia 

This condition affects a number of bones in the body, mostly the long bones. About 20-30% of FD cases are polyostotic. Two thirds of patients exhibit symptoms before the age of 10. Polyostotic FD frequently involves the skull and facial bones, pelvis, spine, and shoulder girdle. The sites of involvement are the femur (91%), tibia (81%), pelvis (78%), ribs, skull and facial bones (50%), upper extremities, lumbar spine, clavicle, and cervical spine, in decreasing order of frequency.

Symptoms

There is a thickening of the long bones and the patient usually complains of persistent bone pain. 

Often, the initial symptom is pain in the involved limb and, spontaneous fracture, or both. Leg-length discrepancy is present to varying degrees in 70% of patients with limb involvement. The weight bearing bones become bowed due to weakening of the structural integrity of the bone. 

The bones of the face and the skull are involved in a majority of the cases and sometimes are unilateral in distribution. If this happens, there is an obvious deformity of the face. 

Sometimes brown lesions called the "cafe-au-lait" spots are present on the skin. Vaginal bleeding is another feature of this condition. Teeth do not erupt into the oral cavity on time. Several hormonal disturbances are also commonly seen. The thyroid, parathyroid and the pituitary as well as the ovary are involved. 

Treatment

Mild cases are satisfactorily treated with surgery. But in severe cases, radiation therapy has been tried with limited success. The lesions have a high potential to turn malignant.