Monostotic Fibrous dysplasia of the bone 

This condition affects mostly people in the age group 10-30. It involves excessive growth of hard fibrous tissue that replaces normal bone tissue in a single bone. Approximately 70-80% of FD cases are monostotic, occurring most frequently in the rib (28%), femur (23%), tibia, craniofacial bones (10-25%), and humerus. With monostotic disease, patients as old as 20 or 30 years are asymptomatic.
The cause of this condition is unknown although several theories have been proposed. One theory attributes this disease to abnormal activity in the bone forming tissues prior to birth. Another theory says any localized infection or trauma gives rise to this disease. In some cases, Monostotic FD of the bone has occurred as an autosomal recessive trait. 

Symptoms

The first sign of the disease is a painless bulging in the affected jaw. As the lesion is constantly expanding, they could lose their balance of contacting the teeth in the opposite jaw, and as a result, there may be disturbance in the teeth as well. . When Fibrous dysplasia occurs in the upper jaw of the maxilla, Monostotic FD is a serious condition. The lesion extends into the maxillary sinus, and on the face. At times it may extend to the base of the skull and obstruct vital nerves, causing irreparable damage. 

Treatment

The treatment of Monostotic FD of the bone is usually radical surgery. This surgery mutilates the entire bone involved, sometimes necessitating block resection as well. In some cases, this condition could lead to osteosarcoma or cancer of the bone.