Olfactory groove meningioma

Clinical History

A 40 year-old woman was admitted to the hospital for headache and bilateral decreased visual acuity for 8 months.
She did not have a specific past medical history or trauma.
The neurological examination was normal.

Imaging Findings

MRI brain revealed a well-circumscribed extra-axial dural-based lobulated mass at the floor of the anterior cranial fossa in the midline overlying the cribriform ethmoid.
The mass had an isointense signal on T1 and T2 (Fig. 1) with homogeneous enhancement after administration of gadoliniumon (Fig. 2), measured approximately 10 x 12 centimetres.

Discussion

Olfactory groove meningioma (OGM) is a benign tumour emerging from the midline of the anterior fossa at the ethmoidal cribriform plate [1]. If large enough, OGM may involve the sellar region and cause blurred vision by compressing the optic nerve and chiasma [2].
These tumours are often responsible for hyperostosis in the bone from where they arise. Further extension into ethmoid sinuses and nasal cavity can occur in 15%-25% of cases [3].
The most common symptoms are usually anosmia headache and visual disturbance [1].
The imaging of olfactory groove meningioma is similar to the rest of meningiomas located elsewhere; they appear slightly hyperdense on non-contrast CT and enhance homogeneously on post-contrast [4].
The MRI signal is isointense to slightly hypointense on T1 and isointense to slightly hyperintense on T2. After contrast meningiomas enhance homogeneously. Calcifications are typical; best demonstrated on CT; on MRI they are best identified on susceptibility-weighted imaging areas of low intensity signals [5].
The treatment of OGM is difficult due to the relationship between the ACA and optic nerves.
The most common approach is the standard fronto-temporal and either unilateral or subfrontal approach [6].

Differential Diagnosis List

Final Diagnosis

Olfactory groove meningioma

URL:	https://www.eurorad.org/case/13561
DOI:	10.1594/EURORAD/CASE.13561
ISSN:	1563-4086