Multicentrical growth of meningiomas: "spatial" or "temporal" phenomenon

Small nodules of neoplastic cells protruding from the arachnoidal layer surrounding an intracranial meningioma, completely independent from the tumor mass, have been observed in three patients who underwent primary surgery. The high rate of recurrence for meningiomas after a seemingly total excision has been many times reported, and related to histological subtypes, tumor site, and hormonal influence. In the past meningotheliomatous cell aggregates protruding from the inner surface of the dura mater at a distance of 3 cm from the insertion of globoid meningiomas have been described, and the concept of "localized dural multifocality" emphasized. Probably this concept has to be enlarged to consider meningioma as a "neoplastic disease" with different grade of expression. The presence of unidentified macroscopic or microscopic clusters of neoplastic cells, lying around, more or less close to, the line of insertion of lesion, could render any attempt to gain a "radical" excision useless.