CincyKidsRad

Cincinnati Children's Radiology

Clear Cell Meningioma (Cns Who Grade 2)

Image description

Axial T2-weighted (image 1), sagittal T1-weighted (image 2), and sagittal postcontrast T1-weighted (image 3) MRI show a large posterior fossa mass (arrow). The mass has an irregular margin with small internal cystic spaces and demonstrates homogeneous enhancement. There is compression of the adjacent medulla and obstruction of the fourth ventricle.

Teaching point

Clear cell meningioma is an uncommon histologic subtype of meningioma and is classified as CNS WHO grade 2. In children and young adults, it more frequently involves the posterior fossa and spinal canal than typical meningiomas. Imaging findings, including homogeneous enhancement and occasional internal cystic spaces, are not specific and do not reliably distinguish this entity from other meningioma subtypes or posterior fossa tumors. The diagnosis is defined histologically by sheets of glycogen-rich clear cells, and the grade 2 designation reflects a higher risk of local recurrence based on clinical behavior rather than imaging appearance.

Diagnosis added by author
Clear Cell Meningioma (Cns Who Grade 2)

Similar cases

Sagittal T1 (image 1) and T1 postcontrast (image 2) MRI images show a large craniopharyngioma extending from the suprasellar region to the pituitary fossa. The tumor is both cystic (arrowhead) and solid (arrow). Craniopharyngiomas appear as a complex suprasellar mass with calcification and wall enhancement. They follow the 90 percent rule with 90 percent of lesions having a cystic component, 90 percent having calcifications, and 90 percent with tumoral enhancement.

Axial (image 1) and coronal (image 2) T1-weighted, axial T2 weighted (image 3), and axial T1-weighted postcontrast (image 4) MRI show the lobulated mass arising from the glomus of the left choroid plexus. The mass diffusely enhances. Choroid plexus papilloma and choroid plexus carcinoma are the most common choroid plexus tumors. They are most commonly diagnosed in children younger than 5 years of age. Papillomas cannot be reliably distinguished from carcinoma. However, the homogeneous enhancement pattern is more common in patients with papilloma.

Axial head CT at the level of the posterior fossa (image 1) in the lateral ventricles (image 2) show a hypodense mass with calcification (arrow) at midline within the posterior fossa near the fourth ventricle. More superiorly, the lateral ventricles are dilated due to obstruction. Sagittal T1 (image 3), T1 post contrast (image 4), and coronal T2 (Image 5) MRI highlight the heterogeneous posterior fossa mass (arrow). At resection, this was shown to represent an ependymoma. Ependymomas account for 10% of pediatric brain tumors and are more common in children younger than 3 years of age. The majority occur within the posterior fossa.

Coronal T1-weighted image (image 1) shows a meningioma (arrow) at the right cerebellar pontine angle. After contrast was administered (image 2), there is diffuse enhancement of the lesion with minimal thickening and irregularity of the adjacent petro clival ligament and lateral margin of the right tentorium. Enhancing cerebellar pontine angle masses typically represent either a vestibular schwannoma or a meningioma. While this is the most common location for a meningioma in the posterior fossa, vestibular schwannomas are more common. Differentiation of the lesions can be difficult. The presence of a dural tail may help to confirm a diagnosis of meningioma.