IS Case 128: Cystic Meningioma
Imaging Sciences URMC 2008
Publication Date: 2009-05-21
Patient is a 52-year-old male who presented with persistent right leg weakness at an outside hospital.
A solid/cystic 3.2 x 3.6 cm mass lesion is seen in the left parafalcine frontal region. This lesion appears to be extra-axial in location with enhancing components seen along the falx. A small dural tail is noted. The lesion also has a cystic component. The ventricles and basal cisterns are preserved. Findings are most consistent with a cystic meningioma.
Meningiomas are the most common primary intracranial tumor of adults with a prevalence of 1.5-2.3% based on autopsy studies. These lesions typically present in mid-life, although they are slow-growing and are typically asymptomatic in most individuals. Meningiomas are more common in women and African Americans.
Meningiomas are extra-axial tumors which arise from the arachnoid meningothelial cap cells. Two basic morphologies of meningioma are recognized. The first being globular-type, in which the lesions are bulbous and well demarcated with a wide dural attachment. The second being en plaque-type, which demonstrate sheet or plaque-like extension covering the dura without invagination into the parenchyma. Loss of one copy of chromosome 22 is the most common chromosomal anomaly found within meningiomas.
MRI is the imaging modality of choice to evaluate meningiomas. On T1WI, meningiomas are usually iso- to slightly hypointense with the brain cortex. A dural tail is identified in 35-80% of cases. Cystic components, necrosis, or hemorrhage may be seen within 8-23% of lesions. On post-contrast T1WI, greater than 95% of meningiomas demonstrate intense and homogenous enhancement. En plaque-type lesions may demonstrate thickened, enhancing dura. Meningiomas may be slightly hypointense or hyperintense to normal cortex on T2WI.
Differential diagnosis includes dural metastasis, granuloma (sarcoid or TB), idiopathic hypertrophic pachymeningitis, and extramedullary hematopoiesis.
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