A skeletal condition known as fibrous dysplasia (FD) is characterized by the replacement of healthy bone with fibrous bone tissue. One bone (monostotic) or several bones could be involved (polyostotic). Any bone in the body might become affected by FD. The skull and face bones are the most typical locations. It is connected to a GNAS1 gene mutation (20q13.2). It begins during childhood and could continue far into adolescence and adulthood. In this case study, a 22-year-old woman was identified as having polyostotic FD based on her clinical, radiological, and histological characteristics.