We presented the case of a 26-year-old woman with a blastic, miliary form of osteosarcomatosis involving the axial skeleton, skull, and long bones to the elbow and knee joint regions who subsequently developed hypocalcemic tetany. Radiologically the lesions mimicked the spread of breast carcinoma, and because of the distribution of the lesions we surmised that the spread was by means of Batson's vertebral plexus of veins. The literature on multiple osteosarcomas was reviewed and an updated clinical subclassification of patients with multiple skeletal osteosarcomas presented.