Considerations on the tendency for calcification in meningiomas

Calcifications in meningotheliomatous and fibromatous meningiomas were demonstrated after maceration under the scanning electron microscope and by pluck preparation. In five predominantly meningotheliomatous and five fibromatous meningiomas vascular features were studied after injection of Indian ink. The influx of calcium into the tumor parenchyma is thought to be related to long vessel loops and parallel coursing vessels which act as a countercurrent multiplication system similar to the loops of Henle in the kidney. Abruptly changing of diameter of vessels reduces the flow rate and enhances the transport of ions across vessels walls. Furthermore, the fine structure of endothelium favors the escape of ions into vessel walls and into parenchyma. Possible consequences of an intratumoral Ca overload are briefly discussed.