title: Tumor-associated FGF-23-induced hypophosphatemic rickets in children: a case report and review of the literature.
abstract: BACKGROUND
  Tumor-associated fibroblast growth factor 23 (FGF-23)-induced hypophosphatemic rickets is a rare but known pediatric entity first described in 1959. It results from local production of phosphatonins by benign and malignant mesenchymal tumors.
  
  
  METHODS
  We report an 8-year-old boy with tumor-associated hypophosphatemic rickets due to paraneoplastic FGF-23 secretion from a benign mesenchymal pelvic-bone tumor. Excessive FGF-23 production was visualized by immunohistochemistry in the resected tumor. Phosphate wasting stopped immediately after tumor resection. We reviewed 26 reports of pediatric patients with tumor-induced hypophosphatemic rickets; paraneoplastic FGF-23 secretion was documented in only three of them. All tumors developed inside bone, were benign in 21/26 cases, and were localized in femur/tibia (13/26), radius/ulna/humerus (7/26), pelvis (4/26), rib (1/26), and craniofacial (1/26) bones. Mean interval between onset of signs and/or symptoms and diagnosis was 34 months.
  
  
  CONCLUSIONS
  In patients with hypophosphatemic rickets acquired beyond infancy, radiologic investigations for bone tumors need to be performed rapidly. In contrast to biochemical screening for increased circulating FGF-23 levels, immunohistochemical confirmation of FGF-23 production in resected tumor tissue can be regarded as being well established.
authors.affiliation: Pediatric Endocrinology, University Children's Hospital Basel, Basel, Switzerland.
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Burckhardt
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schifferli
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Krieg
authors.forename: Daniel
authors.initials: D
authors.lastname: Baumhoer
authors.forename: Gabor
authors.initials: G
authors.lastname: Szinnai
authors.forename: Christoph
authors.initials: C
authors.lastname: Rudin
mesh_terms: D001859:Bone Neoplasms / Q000150:complications* / Q000378:metabolism; D002648:Child; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D063730:Rickets, Hypophosphatemic / Q000209:etiology*
chemical_list: C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23