Disappearance of cerebral calcification as a sign of tumor growth.

Calcification occurs in many benign and malignant neurologic disorders. We describe two patients with cerebral glioma, in whom the disappearance of cerebral calcification was evidence of local malignant change. We discuss the underlying chemical mechanisms that result in tissue calcification, and postulate that calcification may disappear in the presence of a malignant tumor because of a decrease in the pH of the microenvironment.