Tumor-induced osteomalacia: A report of 3 cases and literature review

Objective To improve the understanding of tumor induced osteomalacia (TIO) through analyzing the clinical features, diagnosis and treatment of three cases with this disease. Methods Clinical data about three patients with TIO in our hospital from 2011 to 2017 were respectively analyzed. The first case was a 17-year-old male presented with weakness in both legs and difficulties in walk for 2 years. The second case was a 60-year-old female with recurrent arthralgia in several joints for more than 2 years. The third one was a 63-year-old male complained of weakness in both legs and bone pain for 2 years. All three patients showed hypophosphatemia, hyperphosphaturia, increased level of alkaline phosphates and decreased level of tubular reabsorbtion of phosphorus (TRP). And the imaging results showed osteoporosis and pseudo-fracture in these patients. The tumor was found by PETCT in all the three cases, and was proved by the new 68Ga-DOTA-TATE-PET CT in the third case. Results All the patients were treated with surgery and pathologically confirmed as phosphaturic mesenchymal tumors. The serum phosphorus gradually returned to normal after tumor resection in the first and the third case. As for the second case, the serum phosphorus once returned to normal after surgery. Seven months later, the tumor recurred in situ proved by PET-CT, which cannot be resected by surgery. Conclusion For the patients with bone pain, weakness, and hypophosphatemia, hyperphosphaturia, increased levels of alkaline phosphates, decreased levels of TRP, TIO should be included in the differential diagnosis. Full physical examination and imaging tests are needed to find the tumor, and PET-CT imaging plays an important role in diagnosis.