1. Olfactory Groove Meningioma
Case of the Month - January 2017
Cory Ozimok PGY-2
McMaster University

2. History 31 year old male with progressive hyposmia over 1 year.
Mild morning headaches.
No change in behaviour.
No focal neurological deficits.
Past medical history: remote tonsillectomy, asthma

3. CT Head C-

4. CT Head C-

5. CT Head C- * *

6. CT Head C+

7. Summary of CT Findings
Intrinsically hyperdense lobulated extra-axial mass along the planum sphenoidale measuring 4.2 x 2.9. x 4.3 cm
Central calcification
Associated perilesional edema and mass effect on bifrontal horns and regional convexity sulci
Hyperostosis of jugum sphenoidale (arrow)
Expansion of sphenoid sinus in keeping with pneumosinus dilatans (*)
Avid homogeneous enhancement, displaces ACAs posteriorly

8. MRI
T2 WI
T1 WI
T1 C+
T2 FLAIR

9. MRI
DWI
ADC

10. Summary of MR Findings Well circumscribed
Isointense signal on T1 to brain parenchyma
T2 hyperintense with central low signal (calcification), significant perilesional edema
Avid enhancement
Mild diffusion restriction

11. Case
Due to symptoms, the patient underwent a bifrontal craniotomy for tumour resection with duraplasty
The surgery went well without complications
Headaches resolved

12. Pathology Solid tumour cells forming whorled fascicles.
Cells are oval to spindle shaped with evenly dispersed chromatin and inconspicuous nuclei.
Psamma bodies present.
Diagnosis: Meningioma, Transitional Cell Type

13. Meningiomas
Most common nonglial primary tumours of the CNS and most common extra-axial neoplasm
Account for 15% of all intracranial tumours
Arise from meningothelial cells (arachnoid cap cells)
Common locations:
Supratentorial 90%
Parasaggital and convexities 45%
Sphenoid Ridge 15-20%
Olfactory groove/planum sphenoidale 10%
Juxtasellar 5-10%
Infratentorial 5-10%
CPA most common
Multiple meningiomas assocated with NF2

14. Meningiomas: Radiographic FeaturesCT
60% hyperdense to normal brain
20-30% have calcifications
Avid homogenous enhancement
Hyperostosis 5% (typical for skull base)
MRI
T1 isointense 60-90%
T1 C+ intense homogenous enhancement
T2 isointense to grey matter (50%), hyperintense (35-40%), hypointense (10-15%)
DWI/ADC atypical and malignant subtypes may show greater restricted diffusion

15. Olfactory Groove Meningioma
May demonstrate intranasal or ethmoidal extension
Cerebral edema can be seen in up to 60% of cases
Associated with pneumosinus dilatans
Differential diagnosis
Esthesioneuroblastoma (AKA olfactory neuroblastoma)
Nasal shwanomma
Hemangiopericytoma
Sinonasal SCC

16. References StatDx: A.G. Osborn, M. M. Thurnher. Meningioma.
Radiopaedia: F. Gaillard. Meningioma.
M.P Buetow, P.C. Buetow and J.G. Smirniotopoulos. Typical, Atypical and Misleading Features of Meningioma. Radiographics, 11, (1991).
MedScape: K.M. Fung et al. Meningiomas Pathology.