Erosion of the medial cortex of the proximal humerus. A sign of leukemia on the chest radiograph.

The radiologist may be the first to suggest the diagnosis of leukemia on the basis of erosion of the medial cortex of the proximal metaphysis of the humerus. The upper ends of the humeri are almost always included on a chest radiograph, and frequently this erosion may be the only radiographic sign of the disease.