Giant frontal colliding meningiomas in a child: histopathologic, cytogenetic, and ultrastructural descriptions of a unique case.

Meningiomas in the pediatric population are uncommon primary brain tumors, and rhabdoid meningiomas are exceedingly rare. We describe herein a 16-year-old female who presented with a giant frontal mass with intracranial and extracranial components. Histologic, immunohistochemical, and ultrastructural examinations showed the intracranial tumor to be rhabdoid meningioma, and the extracranial tumor was meningothelial meningioma. Cytogenetic study of the intracranial tumor showed monosomy 22, and the extracranial tumor showed allelic losses at 18p11.32. Because of the different cytogenetic findings and the absence of communication between these two tumors, we concluded that these tumors were separate and represent colliding meningiomas. Furthermore, the rhabdoid meningioma lacked obvious histologic evidence of malignancy. The presence of colliding meningiomas with different cytogenetic abnormalities as well as a rhabdoid meningioma showing no conspicuous evidence of malignancy have not been reported in children before.