Clear cell meningioma (CCM) is an uncommon variant of meningioma, corresponding to WHO grade II. We present two cases of CCMs with anaplastic features in the intracranial and intraspinal region. The first case is a 65-year-old male who gradually developed changes in behavior over a period of 1 year. The second case is a 35-year-old female who presented with a 7-month history of posterior cervicothoracic pain and dysuria for 1 week. Magnetic resonance imaging revealed an intracranial lesion in the right frontal lobe in the male patient, and an intradural extramedullary lesion at C7 in the female patient. On histological examination, both tumors partly exhibited unusual anaplastic appearances with nuclear pleomorphism, high mitotic activity and necrosis, distinct from classical CCMs. Tumor cells were immunoreactive to epithelial membrane antigen (EMA) and vimentin, with a high MIB-1 index up to 40%. Total excision was performed. The male patient was found to have developed local recurrence and lateral ventricle metastasis 3 months after surgery. A diagnosis of CCM with anaplastic features was made (WHO grade III). Based on its aggressive behavior, we recommend postoperative adjuvant radiotherapy or chemotherapy even if total excision of the tumor has been performed, and MRI scans every 3-6 months during the first period of follow-up.
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