title: Identifying the culprit lesion in tumor induced hypophosphatemia, the solution of a clinical enigma.
abstract: Tumor-induced osteomalacia is a rare acquired metabolic bone disorder characterized by isolated renal phosphate wasting due to abnormal tumor production of fibroblast growth factor 23. We report the case of a 59 year old woman referred to our department with a long history of progressive diffuse muscle weakness and pain, generalized bone pains and multiple insufficiency fractures of heels, ankles and hips due to a hypophosphatemic osteomalacia. A fibroblast growth factor 23-producing phosphaturic mesenchymal tumor localized in the left quadriceps femoris muscle was identified 7 years after onset of symptoms. Excision of the tumor resulted in normalization of serum phosphate and fibroblast growth factor 23 levels and in complete resolution of the clinical picture with disappearance of all musculoskeletal symptoms. This case illustrates the diagnostic difficulties in establishing a diagnosis tumor-induced osteomalacia and in identifying the responsible tumor. Our case underscores the clinical need to investigate all patients with persistent musculoskeletal symptoms for hypophosphatemia. A systematic approach is of pivotal importance because early recognition and treatment of the metabolic abnormality can prevent deleterious effects of osteomalacia on the skeleton.
authors.affiliation: Center for Bone Quality and Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands. bot@lumc.nl.
authors.forename: Mathilde M Bruins
authors.identifier: http://orcid.org/0000-0002-7654-4915
authors.initials: MM
authors.lastname: Slot-Steenks
authors.affiliation: Center for Bone Quality and Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
authors.forename: Neveen A T
authors.initials: NA
authors.lastname: Hamdy
authors.affiliation: Center for Bone Quality and Department of Orthopedic Surgery, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
authors.forename: Michiel A J
authors.initials: MA
authors.lastname: van de Sande
authors.affiliation: Department of Radiology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Vriens
authors.affiliation: Department of Pathology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
authors.forename: Arjen H G
authors.initials: AH
authors.lastname: Cleven
authors.affiliation: Center for Bone Quality and Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, The Netherlands.
authors.forename: Natasha M
authors.initials: NM
authors.lastname: Appelman-Dijkstra
mesh_terms: D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D017674:Hypophosphatemia / Q000000981:diagnostic imaging / Q000209:etiology*; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D009372:Neoplasms, Connective Tissue / Q000000981:diagnostic imaging / Q000209:etiology*; D010018:Osteomalacia; D010257:Paraneoplastic Syndromes
chemical_list: C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23
keywords: Fibroblast growth factor 23 (FGF23); Hypophosphatemia; Tumor-induced osteomalacia (TIO)