Tumor-induced osteomalacia (TIO) is a rare disease in which patients suffer from fractures and progressive disabling bone pain and muscle weakness. TIO is caused by the hypersecretion of Fibroblast Growth Factor 23 (FGF23) from rare neoplasms of mesenchymal origin. This case report describes a 29-year-old male with 2 years of low back/hip pain, gait changes, proximal muscle weakness, and multiple stress fractures. Bone densitometry was remarkable for severe osteoporosis, hypophosphatemia was seen on routine labs, and advanced labs demonstrated an “inappropriately normal” FGF23 level. A 68Ga-DOTATATE scan and MRI showed a 1.3 × 1.1 × 1.0 cm intracranial mass. The patient underwent tumor resection by Neurosurgery. Shortly after, laboratory levels normalized, and the patient's symptoms improved drastically. This case exemplifies the notion that TIO can be caused by FGF23 levels within normal limits, the role of 68-Ga DOTATATE imaging for establishing a diagnosis, and that these tumors can arise anywhere—even intracranially. We also review current surgical and nonsurgical treatment options, as well as emerging novel therapeutics.
Bibliographical noteFunding Information:
One of the authors (JMC) is supported by NIGMS of the National Institutes of Health under award number T32GM007347 . The content in this report is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
- Fibroblast growth factor 23
- Paraneoplastic syndrome
- Tumor-induced osteomalacia