Meningioangiomatosis occurring in a young male without neurofibromatosis: with special reference to its histogenesis and loss of heterozygosity in the NF2 gene region.

A 16-year-old young male experienced persistent headache, and brain computed tomography and magnetic resonance imaging showed an abnormal mass with calcification in the right temporal lobe of the cerebrum. The tumor was located in the leptomeninges and cerebral cortex. In the leptomeninges, multiple calcified-fibrous nodules were noted. In this area spindle-shaped cells were arranged in a fascicular or storiform pattern. A few meningioma-like nodules were also present. With continuity of this leptomeningeal lesion, a diffuse infiltrative lesion composed of proliferating perivascular cells and hyalinized small vessels was also present in the cerebral cortex. The proliferating vessels were small and narrowed by proliferation of surrounding spindle-shaped cells. Immunohistochemically, the spindle-shaped cells had strong to moderate positivity for vimentin and CD34 and weak positivity for epithelial membrane antigen and S-100 protein. The maximum Ki67 labeling index was 0.3%. The spindle-shaped cells showed loss of heterozygosity on D17S929 and D17S282 microsatellite markers flanking the NF2 gene. These histopathologic and genetic findings are consistent with meningioangiomatosis, and meningioangiomatosis has been thought to be a neoplastic lesion of meningothelial cells. This is the first report of a genetic alteration in a case of meningioangiomatosis.