Sino-orbital osteoma with osteoblastoma-like features: case reports

Abstract

Most of the orbital osteomas arise from the adjacent paranasal sinuses. Some of them may contain osteoblastoma-like areas and may be misdiagnosed as osteoblastoma, both radiologically as well as histopathologically. Sino-orbital osteomas with osteoblastoma-like features show a typical radiological appearance. They have a distinct zonal pattern, in which less dense osteoblastoma-like areas are located at the base of the lesion and dense mature bone is located at the periphery. These broad-based bone lesions also have a tendency for extracavitary polypoid growths from the paranasal sinus into the adjacent orbit. We report here the CT and MR imaging findings of three cases with sino-orbital osteoma with osteoblastoma-like features.

Giant Paranasal Sinus Osteomas

“…The ''osteoma with osteoblastoma-like features'' histologic subtype is marked by interanastomosing trabeculae and fibrovascular stroma surrounded by osteoblasts and osteoclasts. 14,15 Osteomas with osteoblastoma-like features are more likely to exhibit extracavitary extension, cause visual symptoms, and can be incompletely excised; however, they may be less likely to recur than other osteomas. 14 They also have a distinct radiographic zonal appearance, with lower density, osteoblastoma-like material at the core, and denser mature bone in the periphery.…”

“…14 They also have a distinct radiographic zonal appearance, with lower density, osteoblastoma-like material at the core, and denser mature bone in the periphery. 15 Most paranasal sinus osteomas are asymptomatic and are diagnosed incidentally during radiological evaluation. Their symptoms might include headache, chronic sinusitis, mucocele formation and external deformity.…”

Sino-Orbital Osteoma With Osteoblastoma-Like Features

“…Fibrous dysplasia usually shows a homogenous ground glass appearance and ossifying fibroma is characteristically a well-defined mass with a patchy pattern of osteoblastic and osteolytic areas surrounded by a thin sclerotic margin [9]. While true osteoblastoma and osteoid osteomas are also in the differential, osteoid osteomas are exceptionally uncommon in the craniofacial bones [2].…”

“…CT imaging is better suited than MR images for accurately delineating sino-orbital osteomas with osteoblastoma-like features. With MR imaging, the signal void peripheral zone of the lesion may not be distinguished from air in paranasal sinuses, causing confusion if not evaluated in conjunction with corresponding CT images [9].…”

“…The radiographic differential diagnosis primarily includes fibrous dysplasia and ossifying fibroma, which are both expansile tumors of mixed radiodensity [9]. Fibrous dysplasia usually shows a homogenous ground glass appearance and ossifying fibroma is characteristically a well-defined mass with a patchy pattern of osteoblastic and osteolytic areas surrounded by a thin sclerotic margin [9].…”