Meningioma of the cerebellopontine angle in identical twins: a case report.

Meningiomas in identical twins are extremely rare. To our knowledge, only one previous report of meningiomas in identical twins has been published. We present identical twin sisters with meningiomas. The tumors were located at a similar, but not a common, position (the cerebellopontine angle) in both twins. Histologically, both tumors were diagnosed as meningothelial meningiomas with an angiomatous component. Immunohistochemically, the Ki-67 indices in the two cases were 1.0 and 1.1, and the p53 positive rates were 0.2 and 0.9. The specimens in both cases were reactive to neurofibromin 2 (NF2). A comparative genomic hybridization (CGH) assay revealed an aberration in the long arm of chromosome X, but no aberrations in the long arm of chromosome 22 in either case. These results strongly suggest that genetic aberrations other than NF2 are associated with tumorigenesis in some types of sporadic meningiomas.