A Case of Fibrous Dysplasia of the Ethmoid Bone Forming Intracranial Cyst

Lee, Keum Hyung; Kang, Jun Myung; Lee, Seung Kyun; Ha, Ju Young

Abstract

Fibrous dysplasia is a benign bone lesion characterized by the replacement of the normal substances of the interior of the bone by fibroosseous connective tissue histologically exhibiting varying degrees of osseous metaplasia. Craniofacial dysplasia represents approximately 2.5% of all bone tumors and 7.5% of benign bone tumors. Craniofacial dysplasia frequently affects the maxilla and frontal bone and induces local facial swelling and exophthalmos. The dysplasia has predilection for membranous bone such as femur or tibia, so its origin in the ethmoid is very rare. Recently, we experienced a case of fibrous dysplasia originating in the ethmoid bone extending to intracranial region. Our case demonstrated a huge bony lesion involving right ethmoid, frontal and sphenoid bone and extending to the left frontal area extensively forming a large dumbbell shaped cyst with thin calcified wall. There are no reported cases of fibrous dysplasia forming huge cyst in the intracranial region internationally. Hence, we report a case of fibrous dysplasia of ethmoid sinus forming the intracranial huge cyst.