Bilateral symmetric photon defects in the parietal bones on Tc-99m MDP bone scintigraphy bilateral parietal thinning

A 77-year-old man with small cell carcinoma of the lung underwent Tc-99m MDP bone scintigraphy for evaluation of skeletal metastasis. Bilateral symmetric photon defects in the parietal bones were seen on lateral and vertex images. In addition, symmetric depressions in both parietal regions were seen in the posterior image. The radiographic findings were typical of bilateral parietal thinning. These findings can be mistaken for other pathologic conditions. However, the symmetry and position of the photon defects are generally indicative of bilateral parietal thinning.