Hypophosphatemia related to a neuro-endocrine tumor of the pancreas: A case report.

Background: Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome characterized by hypophosphatemia associated with elevated fibroblast growth factor 23 (FGF23). TIO is primarily caused by benign mesenchymal tumors of the soft tissue and skeleton. Rarely, it is associated with a solid tumor or hematological malignancy. To date, no case of osteomalacia related to pancreatic cancer has been reported in the literature.

Methods: A 77-year-old woman was admitted to the rheumatology department (RD) of the Clermont-Ferrand University Hospital (France) for further evaluation of her hypophosphatemia. The patient reported bone pain, myalgia, and asthenia. Further laboratory tests revealed hyperphosphaturia, normocalcemia, low serum calcitriol, elevated serum alkaline phosphatase (ALP), and elevated plasma parathyroid hormone (PTH). A renal phosphate depletion disorder was suspected as an etiology for this hypophosphatemia. Finally, FGF23 levels were found to be significantly elevated, leading to a definitive diagnosis of pancreatic neuroendocrine tumor.

Conclusions: This is the first report of hypophosphatemic osteomalacia related to pancreatic cancer. Therefore, in the setting of hypophosphatemia associated with renal phosphate wasting and low calcitriol level, plasma FGF23 measurement should be considered.