Answer for BIR CoW 31 Dec 2023
Olfactory groove meningioma
Findings
Well defined T2 isointense extra axial lesion noted in the midline anterior inferior aspect of frontal lobe just above the cribriform plate with broad base towards dura causing buckling of bilateral frontal lobe The lesion shows patchy diffusion restriction The lesion measures 3.6(AP) x 3.8(TR) x 2.7 (CC) cm Confluent T2/FLAIR hyperintensities noted in bilateral frontal region showing no diffusion restriction/blooming foci – Reflecting edema On contrast administration, the lesion shows intense homogenous enhancement Impression Suggestive of olfactory groove meningioma
Discussion
Meningiomas are extra-axial tumors and represent the most common tumor of the meninges. They are a non-glial neoplasm that originates from the meningocytes or arachnoid cap cells of the meninges and are located anywhere that meninges are found, and in some places where only rest cells are presumed to be located. Clinical presentation Headache Paresis Change in mental status Meningiomas may also become clinically apparent due to mass effect depending on their location: supratentorial: 85-90% sphenoid ridge: 15-20% olfactory groove/planum sphenoidale: 10% juxtasellar: 5-10% infratentorial: 5-10% miscellaneous intradural: <5% intraventricular meningioma optic nerve meningioma pineal gland IMAGING Plain radiograph enlarged meningeal artery grooves hyperostosis or lytic regions calcification displacement of calcified pineal gland/choroid plexus due to mass effect CT Non-contrast CT 60% slightly hyperdense to normal brain, the rest are more isodense 20-30% have some calcification >50% demonstrate variable adjacent edema Post-contrast CT 72% brightly and homogeneously contrast enhance malignant or cystic variants demonstrate more heterogeneity/less intense enhancement Hyperostosis (5%) typical for meningiomas that abut the base of the skull need to distinguish reactive hyperostosis from: direct skull vault invasion by adjacent meningioma primary intraosseous meningioma MRI T1 usually isointense to grey matter (60-90%) hypointense to grey matter (10-40%): particularly fibrous, psammomatous variants T1 C+ (Gd): usually intense and homogeneous enhancement T2 usually isointense to grey matter (~50%) hyperintense to grey matter (35-40%) hypointense to grey matter (10-15%) DWI/ADC: grade 2 and 3 tumors may show greater than expected restricted diffusion although this is not universally useful in prospectively predicting histological grade MR spectroscopy: usually does not play a significant role in diagnosis but can help distinguish meningiomas from mimics. Features include: increase in alanine (1.3-1.5 ppm) HELPFUL IMAGING SIGNS CSF cleft sign, which is not specific for meningioma, but helps establish the mass to be extra-axial; loss of this can be seen in grade II and grade III which may suggest brain parenchyma invasion dural tail is seen in 60-72% 2 (note that a dural tail is also seen in other processes) sunburst or spoke-wheel appearance of the vessels white matter buckling sign arterial narrowing typically seen in meningiomas which encase arteries useful sign in parasellar tumors, in distinguishing a meningioma from a pituitary macroadenoma; the latter typically does not narrow vessels peripheral rim of enhancement between meningioma and brain parenchyma in post-contrast 3D-FLAIR can help in distinguishing meningioma from other dural based tumor DSA ANGIOGRAPHY Meningiomas can have a dual blood supply. The majority of tumors are predominantly supplied by meningeal vessels; these are responsible for the sunburst or spoke-wheel pattern observed on MRI/DSA. Some tumors also have a significant pial supply to the periphery of a tumor. A well known angiographic sign of meningiomas is the mother-in-law sign, in which the tumor contrast blush "comes early, stays late, and is very dense". Differential Diagnosis solitary fibrous tumors of the dura more aggressive often destroying bone extensive peripheral vascularity more microlobulation dural metastases(e.g. breast cancer) Specific location differentials include: cerebellopontine angle acoustic schwannoma pituitary region pituitary macroadenoma craniopharyngioma base of the skull hypertrophic pachymeningitis extramedullary hematopoiesis In the setting of hyperostosis consider: Paget's disease fibrous dysplasia sclerotic metastases
REFERENCES
Robert I. Grossman, David M. Yousem. Neuroradiology. (2003) ISBN: 9780323005081 - Google Books 2. Wallace E. The Dural Tail Sign. Radiology. 2004;233(1):56-57. doi:10.1148/radiol.2331021332 3. Elster A, Challa V, Gilbert T, Richardson D, Contento J. Meningiomas: MR and Histopathologic Features. Radiology. 1989;170(3 Pt 1):857-62. doi:10.1148/radiology.170.3.2916043
Findings
Well defined T2 isointense extra axial lesion noted in the midline anterior inferior aspect of frontal lobe just above the cribriform plate with broad base towards dura causing buckling of bilateral frontal lobe The lesion shows patchy diffusion restriction The lesion measures 3.6(AP) x 3.8(TR) x 2.7 (CC) cm Confluent T2/FLAIR hyperintensities noted in bilateral frontal region showing no diffusion restriction/blooming foci – Reflecting edema On contrast administration, the lesion shows intense homogenous enhancement Impression Suggestive of olfactory groove meningioma
Discussion
Meningiomas are extra-axial tumors and represent the most common tumor of the meninges. They are a non-glial neoplasm that originates from the meningocytes or arachnoid cap cells of the meninges and are located anywhere that meninges are found, and in some places where only rest cells are presumed to be located. Clinical presentation Headache Paresis Change in mental status Meningiomas may also become clinically apparent due to mass effect depending on their location: supratentorial: 85-90% sphenoid ridge: 15-20% olfactory groove/planum sphenoidale: 10% juxtasellar: 5-10% infratentorial: 5-10% miscellaneous intradural: <5% intraventricular meningioma optic nerve meningioma pineal gland IMAGING Plain radiograph enlarged meningeal artery grooves hyperostosis or lytic regions calcification displacement of calcified pineal gland/choroid plexus due to mass effect CT Non-contrast CT 60% slightly hyperdense to normal brain, the rest are more isodense 20-30% have some calcification >50% demonstrate variable adjacent edema Post-contrast CT 72% brightly and homogeneously contrast enhance malignant or cystic variants demonstrate more heterogeneity/less intense enhancement Hyperostosis (5%) typical for meningiomas that abut the base of the skull need to distinguish reactive hyperostosis from: direct skull vault invasion by adjacent meningioma primary intraosseous meningioma MRI T1 usually isointense to grey matter (60-90%) hypointense to grey matter (10-40%): particularly fibrous, psammomatous variants T1 C+ (Gd): usually intense and homogeneous enhancement T2 usually isointense to grey matter (~50%) hyperintense to grey matter (35-40%) hypointense to grey matter (10-15%) DWI/ADC: grade 2 and 3 tumors may show greater than expected restricted diffusion although this is not universally useful in prospectively predicting histological grade MR spectroscopy: usually does not play a significant role in diagnosis but can help distinguish meningiomas from mimics. Features include: increase in alanine (1.3-1.5 ppm) HELPFUL IMAGING SIGNS CSF cleft sign, which is not specific for meningioma, but helps establish the mass to be extra-axial; loss of this can be seen in grade II and grade III which may suggest brain parenchyma invasion dural tail is seen in 60-72% 2 (note that a dural tail is also seen in other processes) sunburst or spoke-wheel appearance of the vessels white matter buckling sign arterial narrowing typically seen in meningiomas which encase arteries useful sign in parasellar tumors, in distinguishing a meningioma from a pituitary macroadenoma; the latter typically does not narrow vessels peripheral rim of enhancement between meningioma and brain parenchyma in post-contrast 3D-FLAIR can help in distinguishing meningioma from other dural based tumor DSA ANGIOGRAPHY Meningiomas can have a dual blood supply. The majority of tumors are predominantly supplied by meningeal vessels; these are responsible for the sunburst or spoke-wheel pattern observed on MRI/DSA. Some tumors also have a significant pial supply to the periphery of a tumor. A well known angiographic sign of meningiomas is the mother-in-law sign, in which the tumor contrast blush "comes early, stays late, and is very dense". Differential Diagnosis solitary fibrous tumors of the dura more aggressive often destroying bone extensive peripheral vascularity more microlobulation dural metastases(e.g. breast cancer) Specific location differentials include: cerebellopontine angle acoustic schwannoma pituitary region pituitary macroadenoma craniopharyngioma base of the skull hypertrophic pachymeningitis extramedullary hematopoiesis In the setting of hyperostosis consider: Paget's disease fibrous dysplasia sclerotic metastases
REFERENCES
Robert I. Grossman, David M. Yousem. Neuroradiology. (2003) ISBN: 9780323005081 - Google Books 2. Wallace E. The Dural Tail Sign. Radiology. 2004;233(1):56-57. doi:10.1148/radiol.2331021332 3. Elster A, Challa V, Gilbert T, Richardson D, Contento J. Meningiomas: MR and Histopathologic Features. Radiology. 1989;170(3 Pt 1):857-62. doi:10.1148/radiology.170.3.2916043
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!