Delayed diagnosis of occult phosphaturic mesenchymal tumor in the foot

Abstract Phosphaturic mesenchymal tumors are the main cause of tumor-induced osteomalacia, a distinctive paraneoplastic syndrome mediated by overproduction of fibroblast growth factor 23, that leads to renal phosphate wasting and hypophosphatemia. Diagnosis of this mesenchymal tumors is difficult and usually delayed for several years. We present the case of a 70-years-old-male with generalized bone pain, multiple pathological fractures and persistent hypophosphatemia, diagnosed with tumor-induced osteomalacia after 4 years of the onset of symptoms. The tumor was localized in the forefoot using Gallium 68-DOTANOC positron emission tomography-computed tomography and successfully surgically treated. This case report highlights the importance of recognizing these rare tumors, as early diagnosis can prevent long-term morbidity.