The Findings on Bone Scintigraphy in Patients With Suspected Tumor-Induced Osteomalacia Should Not Be Overlooked

Purpose Tumor-induced osteomalacia (TIO) is a chronic, devastating disease. The causative tumor is usually a small benign one that is very difficult to localize. Because the presenting symptoms include diffuse bone pain, a bone scintigraphy is commonly performed to determine the cause of the pain before TIO is suspected. In this retrospective investigation, we tried to assess whether bone scintigraphy acquired will be helpful in the eventual identification of the culprit tumor. Methods The images of bone scan and clinical charts of total 91 patients with confirmed TIO were retrospectively reviewed. The image findings were compared with the results of other imaging studies, surgical notes, histopathologic examinations and clinical follow-ups. Results In 76.9% (70 of 91) of the patients, the findings of bone scintigraphy did not correspond to the sites of the causative tumors, which were subsequently located. However, in 23.1% of the patients (21 of 91), the sites of the causative tumors corresponded to one of the abnormal technetium 99m-methyl diphosphonate activity on bone scintigraphy. More importantly, 6 tumors corresponded to the dominant activity on bone scintigraphy. Conclusions Although findings of whole-body scintigraphy are nonspecific in patients with TIO, careful evaluation of bone scintigraphy results can be helpful in guiding further evaluation in some patients.