title: Tumor-induced osteomalacia: benign tumor recurrence after two surgical resections at two different medical institutions.
abstract: OBJECTIVE
  To describe an exceedingly rare case of tumor-induced osteomalacia (TIO) caused by a benign phosphaturic mesenchymal tumor that recurred after two surgical resections at two different medical institutions.
  
  
  METHODS
  A 69-year-old man complained of a 3-year history of persistent whole body pain and presented with hypophosphatemia, elevated serum levels of bone-specific alkaline phosphatase and fibroblast growth factor-23 (FGF-23), and multiple fractures. The patient was suspected of having TIO. We conducted the following diagnostic modalities considered useful to detect the tumor: serum FGF-23 level measurement in the extremities, positron emission tomography (PET)-computed tomography (CT),and magnetic resonance imaging (MRI).
  
  
  RESULTS
  The causative tumor could be detected in the right humerus not by venous catheterization for serum FGF-23 level measurement but by the combination of PET-CT and MRI. The authors, who had successfully treated two patients with TIO, visually confirmed the absence of any tumor residue during tumorectomy. Nevertheless, the tumor recurred after surgery. The residual tumor could be localized in the right humerus not by PET-CT but by the combination of superficial venous sampling at 10 sites and MRI. The residual tumor recurred after the second tumorectomy at another hospital. This patient indicates that the possibility--a benign causative tumor may not be completely resected by surgery--cannot be ruled out thoroughly.
  
  
  CONCLUSIONS
  Superficial venous sampling at multiple sites may be a surrogate for venous catheterization. Patients with TIO should be meticulously followed-up after surgery to detect any residual tumor by periodic biochemical monitoring and by imaging modalities accordingly.
authors.affiliation: Department of Endocrinology and Diabetes, Saitama Medical University, Saitama 350-0495, Japan. shigemitsuyasuda@msn.com
authors.forename: Shigemitsu
authors.initials: S
authors.lastname: Yasuda
authors.forename: Seiki
authors.initials: S
authors.lastname: Wada
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Kono
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyajima
authors.forename: Hiromi
authors.initials: H
authors.lastname: Oda
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Katayama
authors.forename: Takuya
authors.initials: T
authors.lastname: Awata
mesh_terms: D000368:Aged; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D006801:Humans; D017674:Hypophosphatemia / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D009372:Neoplasms, Connective Tissue / Q000097:blood / Q000175:diagnosis*; D010018:Osteomalacia; D010257:Paraneoplastic Syndromes; D049268:Positron-Emission Tomography
chemical_list: C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23