Oncogenic Osteomalacia as a Harbinger of Recurrent Osteosarcoma

Discussion. Oncogenic osteomalacia is a rare paraneoplastic syndrome of skeletal demineralization from renal phosphate loss. Patients with this disorder have the characteristic clinical, laboratory, and radiographic findings of hyperphosphaturic osteomalacia. Although the pathophysiology has not yet been clearly delineated, a humoral factor produced by the tumor is suspected to be the cause. Purpose. We report the first case of oncogenic osteomalacia that improved with chemotherapy, discuss this paraneoplastic syndrome, and review the medical literature regarding its etiology.