Meningioma Mimicking Fibrous Dysplasia

Abstract

Despite being among the common primary intracranial tumors, intraosseous craniofacial meningioma is the least common subtype of meningioma accounting for only 1-2% of intracranial meningiomas. Interestingly, it can display clinical and radiologic features that can be confused for fibrous dysplasia. Scan imaging and biopsy are crucial for the diagnosis as well as for further proper treatment. We report a case of unilateral eye proptosis and optic neuropathy which was initially thought for fibrous dysplasia. Later the histopathology revealed meningioma grade 1. As the clinical presentations are almost undifferentiated, diagnosis and further prompt treatment are challenging.

Intraosseous Meningioma Mimicking Fibrous Dysplasia

“…Meningiomas are the most common primary brain tumor in adults, but the primary intraosseous involvement of the craniofacial bones is rare, occurring in less than 2% of patients (1). Intraosseous meningiomas (IM) can be isolated, have an en plaque component, or may be part of a larger extracranial mass with osseous invasion.…”

“…The imaging of IM is often complicated by marked hyperostosis, which can lead to misidentification as other lesions presenting with a diffuse sclerotic pattern such as FD, a more common developmental process that also has predilection for the craniofacial bones and skull base. Both IM and FD have a female predominance and can share symptoms related to bony expansion of the craniofacial bones or narrowing of the cranial foramina, such as visual changes, proptosis, or hearing loss (1). CHL is more common in FD, seen in 66% of patients versus 15% of patients with IM (2,3).…”

“…CHL is more common in FD, seen in 66% of patients versus 15% of patients with IM (2,3). Additionally, the incidence of meningioma increases with age, whereas FD tends to present in adolescents or early adulthood (1).…”

Intraosseous meningioma of the orbital roof

“…Primary intraosseous or intradiploic meningioma is a rare variety of meningioma that accounts for about 1% of all meningiomas. 13,14 Marwah et al 15 defined a meningioma that develops in the skull as a primary intraosseous meningioma and the diagnostic criteria included lesions which have the histological features of a meningioma; lesions located in the epidural or skull region; and without involvement of brain, arachnoid or dura mater tissue. 15,16 Lang et al 17 classify primary extradural meningioma into three categories.…”

“…Another lesion to take into account in the differential diagnosis is chondrosarcoma, the latter progresses rapidly, sometimes it canoccur in the orbital wall, it is known for its aggressive behavior with a high recurrence rate and causes distant metastasis. [12][13][14]18 Most of these tumors are benign but malignant transformation is also described. The histological picture in most of the cases reported so far, including this case, revealed a psammomatous meningioma with invasion of the bone by meningiomatous tissue.…”