Clear cell meningioma

Clear cell meningiomas are a histological variant of meningioma with poorer prognosis and a higher rate of recurrence. They are therefore considered WHO grade 2 tumours, regardless of mitotic index, cellular atypia/anaplasia, or presence of brain invasion. 

Epidemiology

Clear cell meningiomas have been reported to occur at a younger age group (mean age of ~30 years) and are more frequently located within the spinal canal (see spinal meningioma) and posterior fossa ^1-3. No convincing predilection for either gender has been reported ¹. 

Clinical presentation

Although generally, they present in a similar fashion to other meningiomas, their predilection for the posterior fossa and spinal canal clearly has implication to the presenting symptoms.

Pathology

Clear cell meningiomas appear similar to meningothelial (syncytial) meningiomas. However, the tumour cells have vacuolated cytoplasm; thus the moniker 'clear cell' ¹. Histologically these tumours resemble other clear cell tumours such as oligodendroglioma, hemangioblastoma, germinoma, pleomorphic xanthoastrocytoma (PXA), clear-cell ependymoma and metastases from renal cell carcinoma ¹. 

Radiographic features

Radiographic features are similar to those of the more common 'typical' meningiomas and are thus not repeated here. 

Treatment and prognosis

Despite benign appearing histology, clear cell meningiomas have a tendency to recur locally (higher than 60% in some series, and particularly high in intracranial disease) and metastasise within the CSF space ^1-3.