Ricerc@Sapienza

Mesenchymal Phosphaturic Tumors (MPTs) are the most common cause of an uncommon paraneoplastic syndrome known as Tumor Induced Osteomalacia (TIO). They typically occur in soft tissues and bone and in less than 5% in the head and neck region where the naso-ethmoidal is rarely involved. The presentation of the case includes also the analysis of the expression by RT-PCR of two “phosphatonins” that are known to be involved in the development of the syndrome.

We investigated the usefulness of fibroblast growth factor 23 (FGF23) intraoperative assay to monitor tumor resection in patients with oncogenic osteomalacia. A 33-year-old man with 5 years’ history of lumbar and pelvis pain together with multiple vertebral fractures was admitted to our hospital. He was diagnosed with ankylosing spondylitis 1 year before. Laboratory investigation showed low tubular reabsorption of phosphate (0.41 mmol/L) despite chronic hypophosphatemia (0.39/L). Increased plasma values of FGF23 (673 pg/mL; n.v. < 95 pg/mL) were also observed.