Unusual scintigraphic findings in a case of treated monostotic Paget's disease

A 72-year-old woman with Paget's disease underwent therapy with EHDP for 5 years. A Tc-99m MDP bone scan demonstrated an unusual image in the right femur. The upper one third of the femur was thickened, bowed, and had diffuse and mild uptake. This corresponded to radiographic findings of mixed or chronic Paget's disease. A long area of intense and homogenous uptake was found immediately distal, and with a sharp demarcation. Alterations typical of the lytic phase of Paget's disease were seen on radiographs. The overall lesion in this patient thus demonstrated two distinct patterns, both radiographically and on bone imaging. It is conjectural whether this was related to the chronic use of a diphosphonate in therapy.