Evidence for clonal spread in the development of multiple meningiomas.

Meningiomas are common intracranial tumors that arise from the arachnoid cells of the meninges. Occasionally patients develop multiple meningiomas. Because the underlying mechanism of multiple meningioma formation is unknown, the authors examined the pattern of X chromosome inactivation in multiple meningiomas. Fifteen intracranial meningiomas were resected in four patients with multiple meningiomas to determine whether the tumors in patients with multiple meningiomas originate from a common progenitor cell or arise independently. Specimens were examined using polymerase chain reaction assays to detect the pattern of X chromosome inactivation. In each patient, all tumors showed inactivation of the same X chromosome, suggesting that tumors arose from the same clone of cells (p < 0.0005). The authors conclude that multiple meningiomas arise from the uncontrolled spread of a single progenitor cell.