It is a bit unusual to see a periosteal reaction with protate mets, or in any older individual for that matter because the periosteum is tightly adhered to bone and limited in its ability to react quickly or robustly to an underlying pathology. The blastic changes in this case however are none-the-less characteristic, and blastic mets from prostatic carcinoma must be the #1 differential diagnosis in an elderly male with patchy sclerotic bone changes.