Local changes in the skull overlying meningeal endotheliomas occur sufficiently often to make their recognition a point of considerable value in distinguishing between endotheliomas and other brain tumors. The changes are of two types, localized bony thickening and local erosion.
LOCALIZED BONY THICKENING
Much the commoner change is localized bony thickening. Cushing1 found that it was present in some degree in at least 25 per cent. of his eighty cases of meningeal endothelioma. Inasmuch as the proportion of endotheliomas to gliomas is between one to two and one to four (seventy-five meningeal tumors to 142 gliomas in Tooth's2 series, and eighty endotheliomas to 312 gliomas in Cushing's series), the detection of the hyperostosis would be of value in distinguishing between these two main groups of tumors in one out of every eight to sixteen cases.Virchow,3 in 1864, stated that he had several times noticed thickening of