Gallium-67 citrate localization in osteoclast nuclei of Paget's disease of bone

Gallium-67 citrate scintigraphy has been used to indicate the extent of bone involvement in patients with Paget's disease of bone and is an excellent marker in monitoring the effects of specific therapy. Since gallium uptake is dependent on cellular function, autoradiographic techniques can be applied to cells of Paget's lesions to understand better the mechanism of [67Ga]citrate uptake. Bone biopsies were obtained from sites of increased uptake using [67Ga]citrate scintigraphy in two patients with Paget's disease. In both patients electron microscopic autoradiographs demonstrated a high concentration of silver grains over the nuclei of osteoclasts. The cellular mechanism is unknown but may be related to the known inhibitory effect of calcitonin on osteoclast activity. The association of [67Ga]citrate with the nucleus of the osteoclasts is unique and different from tumor cells in which there is a high association of [67Ga]citrate with the lysosome fraction within the cytoplasm.