Fibrous Dysplasia of Ethmoid

Fibrous dysplasia (FD) is a benign skeletal disorder in which abnormally overgrowing bony lesion replaces the normal bone. It can affect one bone (monostotic form) or multiple bones (polyostotic form). The craniofacial bones are involved in about 10% of subjects with monostotic FD. Among FD of the head and neck, the maxilla and mandible are the most frequent sites to be involved. However, its occurrence in the sinonasal tract is very rare. We report a case of a large monostotic FD of the ethmoid bone in a 29-year-old woman. The lesion was removed by lateral rhinotomy approach and pathology proved to be FD.