Phosphaturic mesenchymal tumor

Phosphaturic mesenchymal tumor is an extremely rare benign neoplasm of soft tissue and bone that inappropriately produces fibroblast growth factor 23. This tumor may cause tumor-induced osteomalacia, a paraneoplastic syndrome, by the secretion of FGF23, which has phosphaturic activity (by inhibition of renal tubular reabsorption of phosphate and renal conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D). The paraneoplastic effects can be debilitating and are only reversed on discovery and surgical resection of the tumour.