Clinical and bone density outcomes of tumor-induced osteomalacia after treatment

Objective: To report the outcomes of tumor-induced osteomalacia after treatment, particularly related to recovery of bone mass. Methods: We review the clinical course of a 61-year-old man extremely debilitated from multiple fractures and neuromuscular weakness due to tumor-induced osteomalacia and report the changes in biochemical markers and bone density after removal of the causative neoplasm. Results: At the time of diagnosis, the patient's serum phosphorus and 1,25 dihydroxyvitamin D levels were depressed, and his fibroblast growth factor-23 level was markedly elevated. These values normalized 2 days after surgery and remained within their respective reference ranges 4 and 12 months after resection of a mesenchymal tumor. Lumbar bone density values (T-scores) were 0.445 g/cm² (-5.9) preoperatively, 0.939 g/cm ² (-1.4) 4 months after surgery, and 1.152 g/cm² (0.7) 12 months after surgery. Left femoral neck values at the same time points were 0.525 g/cm² (-3.0), 1.035 g/cm² (-0.8), and 1.184 g/cm² (1.9). Ultra-distal radius values at the same time points were 0.128 g/cm² (-7.0), 0.191 g/cm² (-5.9), and 0.259 g/cm² (-4.8). In addition, he recovered neuromuscular function and was able to leave his wheelchair. Conclusion: Tumor-induced osteomalacia can be an extremely debilitating disease. With successful localization, identification, and resection of the neoplasm, bone mass and physical function can recover.