Figure 18a. Evolution of a leptomeningeal cyst. (a) Lateral skull radiograph obtained at 9 weeks of age shows an acute parietal fracture. (b) Lateral skull radiograph obtained at 7 months of age shows that the fracture has healed except for a well-defined lucent defect in the parietal bone, which represents the calvarial defect at the site of a leptomeningeal cyst.