"Non-phosphaturic" variant of phosphaturic mesenchymal tumor of the middle ear expressing multiple phosphatonins

Phosphaturic mesenchymal tumors (PMTs) are rare tumors commonly arising in soft tissues and bones. They are the main cause of tumor-induced osteomalacia (TIO), a paraneoplastic syndrome caused by production of FGF23 and other phosphatonins. “Non-phosphaturic” variant of PMTs (i.e., not associated with TIO) have been also reported. We describe a patient with a PMT of the middle ear, a very rare site for PMTs, in which TIO failed to develop although three phosphatonins were expressed.