Craniofacial fibrous dysplasia with aneurysmal bone cyst: A rare coexistence

Abstract

Fibrous dysplasia (FD) is a developmental anomaly in which the normal bone marrow is replaced by fibro-osseous tissue. Fibrous dysplasia can affect either single (monostotic) bone or multiple (polyostotic) bones. Craniofacial FD is a monostotic FD involving the craniofacial bones. However, CFD is one of the rare forms of FD. Aneurysmal bone cyst (ABC) is a rare non-neoplastic bone lesion. ABCs are expansile lytic lesions composed of numerous blood-filled channels and cystic spaces that mostly involve the long bones and vertebrae and occur rarely in the craniofacial bones. ABCs can occur either as a primary bony lesion or secondary to various pre-existing benign and malignant bone tumors like fibrous dysplasia. Concomitant occurrence of FD and ABC is rare with only few cases reported in the literature. Here, we report on a case of ABC in a 24-year-old woman who had presented with right frontal and facial swelling for over 6 years followed by proptosis of right eye. Computed tomography revealed an expansile lytic lesion with peripheral ground glass densities involving the body and greater wing of sphenoid, lateral wall of orbit, squamous part of temporal bone with associated thinning and rarefaction of the bony walls. Further, MRI of the same patient revealed multiple cystic spaces some of them showing fluid-fluid levels within.