A FGF23-Positive Maxillary Sinus Tumor Associated with Oncogenic Osteomalacia

ABSTRACT

Oncogenic osteomalacia is a rare acquired paraneoplastic syndrome caused by excessive renal phosphate wasting that causes hypophosphatemia and osteomalacia. Fibroblast growth factor 23 (FGF23) has been identified as the causative factor of oncogenic osteomalacia and is also known as its diagnostic marker in immunohistochemistry studies. Recently, the authors of the present study experienced a female patient with a prolonged history of osteomalacia; a rare maxillary sinus tumor was confirmed by anti-FGF23 immunohistochemical staining as the causative tumor. The present case is the first reported case in Korea to have been diagnosed as a head and neck tumor associated with oncogenic osteomalacia according to anti-FGF23 immunohistochemical staining.