Metaplastic meningioma with cartilaginous differentiation

A meningioma with cartilaginous areas is described. The tumour arose in the region of the right sphenoid wing in a 74-year-old woman. Histologically, it showed large areas of a typical meningothelial meningioma, among which n umerous cartilaginous islands and some chondroid regions, obviously of inte rmediate (meningothelial/cartilaginous) differentiation, could be seen. Car tilaginous tumour areas showed lower MIB1-labelling indices than typical me ningioma regions, where an increased proliferative activity was seen focall y. The current WHO classification lists such tumours as metaplastic meningi omas, reflecting the potential of meningioma cells for mesenchymal differen tiation. Metaplastic meningiomas may show different metaplasias (xanthomato us, osseous, lipomatous, cartilaginous, etc.). Extensive cartilaginous meta plasias are very uncommon. Identification of typical meningioma areas is th e key for the diagnosis of this meningioma variant.