Intraparenchymal cystic chordoid meningioma: a case report and review of the literature.

Meningiomas usually present as benign tumors corresponding to WHO grade I. The development of the intraparenchymal chordoid variant of meningiomas with cyst formation in the CNS is extremely rare. We report a case of cystic chordoid meningioma in a middle-aged man occurring in the brain parenchyma of the left temporal region. The tumor exhibited a marked peritumoral cyst, with contrast enhancement on MRI in accordance with type 2 of Zee's classification of cystic meningioma. Histologically, the tumor displays a typical chordoid structure with trabeculae or cords of eosinophilic vaculoated cells in the abundant mucoid matrix. Tumor cells are diffusely positive for epithelial membrane antigen (EMA), vimentin and focally positive for D2-40, but lack immunoreactivity for cytokeratin (CK) and GFAP. MIB-1 labeling is low, focally accounting for 2% of the tumor. A diagnosis of primary intraparenchymal cystic chordoid meningioma (WHO grade II) was made. There was no evidence of tumor recurrence during the postoperative 6-month follow-up period. To our knowledge, there is no report describing the radiological and histological characteristics of cystic chordoid meningioma entirely presenting in the brain parenchyma. In addition, the biological behavior and histological differential diagnoses of this tumor are discussed.