Unusual Association of Partial Fanconi Syndrome and Tumor-Induced Osteomalacia Revealed by Multiple Vertebral Fractures

Article Article scientifique Rapport de cas Unusual Association of Partial Fanconi Syndrome and Tumor-Induced Osteomalacia Revealed by Multiple Vertebral Fractures eng 2025-01-31 2025-01-31 author Debrach Anne Cécile 0000-0001-7294-9125 Division of Bone Diseases, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland. annececile.debrach@hcuge.ch. 909766 author Coen Matteo 0000-0002-6156-1691 Division of General Internal Medicine, Department of Medicine, University Hospitals, Geneva, Switzerland.,Unit of Development and Research in Medical Education, Faculty of Medicine, University of Geneva, Geneva, Switzerland. 601519 Département de médecine (DEMED) author De Seigneux Matthey Sophie Division of Nephrology and Hypertension, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland. 105798 Département de médecine (DEMED) author Saiji Essia Division of Pathology, Geneva University Hospitals, Geneva, Switzerland. 664737 author Boudabbous Sana Division of Radiology, Department of Diagnosis, Geneva University Hospitals, Geneva, Switzerland. 800627 Département de radiologie et informatique médicale (RADIO) author Willi Jean-Pierre Division of Nuclear Medicine, Geneva University Hospitals, Geneva, Switzerland. 563233 author Serratrice Jacques Division of General Internal Medicine, Department of Medicine, University Hospitals, Geneva, Switzerland. 836481 Département de médecine (DEMED) author Genevay Stéphane 0000-0003-4752-3186 Division of Rheumatology, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland. 37330 Département de médecine (DEMED) author Biver Emmanuel Division of Bone Diseases, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland. 714511 Département de médecine (DEMED) 36 10.1007/s00223-025-01344-2 39888445 0171-967X PMC11785680 https://link.springer.com/article/10.1007/s00223-025-01344-2 Tumor-induced osteomalacia (TIO) is a rare acquired paraneoplastic syndrome caused by a mesenchymal tumor secreting a phosphaturic hormone called FGF23. Patients present with bone pain, fragility fractures and muscle weakness. Biochemical results show hypophosphatemia, raised serum alkaline phosphatase and reduced calcitriol. We report the case of a 44-year-old man who presented to the Emergency Departement with acute low back pain revealing extensive subchondral fractures between D2 and L5. Investigations showed partial Fanconi syndrome; nevertheless, he had profound hypophosphatemia, low 1,25-OH vitamin D and raised FGF23 levels suggesting a diagnosis of tumor-induced osteomalacia. A subcutaneous lesion was identified in the left leg on a PET-CT initially performed to rule out malignancy in the context of Fanconi syndrome. Tumorectomy enabled complete resolution of the electrolyte disturbances within days of surgery. This case shows that TIO may present as partial Fanconi syndrome, highlighting the importance of testing other electrolytes in cases of hypophosphatemia and the need to look for TIO in cases of partial Fanconi with severe hypophosphatemia. Fanconi syndrome Fractures Tumor-induced osteomalacia Hypophosphatemia Humans Osteomalacia / etiology Male Adult Fanconi Syndrome / complications Fanconi Syndrome / diagnosis Fanconi Syndrome / etiology Paraneoplastic Syndromes / etiology Fibroblast Growth Factor-23 Spinal Fractures / complications Spinal Fractures / etiology Spinal Fractures / diagnosis Neoplasms, Connective Tissue / etiology Neoplasms, Connective Tissue / diagnosis Neoplasms, Connective Tissue / complications Hypophosphatemia / etiology Fractures, Multiple / etiology Fractures, Multiple / complications Dewey 616.0757 Dewey 610/370 Dewey 616 Dewey 616.07 56 Département de médecine 221 48 Unité de développement et de recherche en éducation médicale 204 137 Département de pathologie et immunologie 21F 62 Département de radiologie et informatique médicale 227 false 289 Métabolisme osseux 544 897 Insuffisance rénale chronique 941 Calcified tissue international 116 1 73164b06-3436-4f55-9504-c259d2231276 Article (Published version) Public Article_scientifique_from_europePmc.pdf 746772 application/pdf CC BY-4.0 8366a8d4375996f78c79d3152b83aa8e1c4df94a0e7488595792c55a143e2df0 openAccess Faculté de médecine / Section de médecine clinique / Département de médecine Faculté de médecine / Unité de développement et de recherche en éducation médicale Faculté de médecine / Section de médecine fondamentale / Département de pathologie et immunologie Faculté de médecine / Section de médecine clinique / Département de radiologie et informatique médicale

Title	Published in	Year	Views	Downloads

Unusual Association of Partial Fanconi Syndrome and Tumor-Induced Osteomalacia Revealed by Multiple Vertebral Fractures	Calcified tissue international	2025	63	55
Maladies osseuses : ce qui a changé en 2023	Revue médicale suisse	2024	114	3

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Debrach, Anne Cécile