Skeletal Metastasis in Renal Cell Carcinoma: Photon Deficiency on Bone Scintigraphy

Bone scintigraphy with 99mTc-labeled phosphorous compound is an excellent technique for the detection of bone metastasis. Bone metastases are usually visualized as multiple hot spots on bone scintigraphy. However, photon deficiency in the metastatic lesion on bone scintigrams is reported in few cases with malignancy. In this study, we have evaluated the photopenic bone metastasis from renal cell carcinoma by the radiographic and computed tomographic examinations. Photon deficient metastatic lesions were seen on bone scintigraphy in 5 patients with renal cell carcinoma. All of the photon deficient lesions were osteolytic on bone radiography and computed tomography. The pure photon deficient lesions not associated with surrounding hot margins were seen on the thoracic vertebrae and rib and the ones with surrounding hot margins were seen on the sternum, pelvis and femur. This difference may be due to the differences in the growth rate of the tumor and reactive hyperemia and new bone formation in the metastatic lesions