Tumor-induced osteomalacia: experience from a South American academic center.
The majority of tumor-induced osteomalacia cases have been reported in the Northern Hemisphere and Asia. In this first series of South American patients, we show that the clinical presentation and sensitivity of plasmatic fibroblast growth factor 23 and somatostatin analog-based imaging are similar to those described in other populations.



Describe the experience of clinical presentation, diagnostic study, and treatment of patients with tumor-induced osteomalacia (TIO) in a South American academic center in comparison to literature.



Analysis of the records of patients diagnosed with TIO. The clinical presentation, diagnostic studies, and treatment were analyzed. Fibroblast growth factor 23 (FGF23) was measured by ELISA.



Six patients were diagnosed with TIO during the studied period. The patients' median age was 53 years (range 22-64). All patients presented with weakness and pain in the extremities. Four experienced fractures during their evolution. The median time to diagnosis was 4.5 years (1-20). Biochemical studies showed hypophosphatemia, median of 1.4 mg/dL (1.2-1.6), with low maximum rates of tubular reabsorption of phosphate adjusted for glomerular filtration rate. FGF23 was elevated in 4/6 patients and inappropriately normal in the other two. In three patients, the location of the tumor was clinically evident and confirmed with anatomical imaging. In the remaining patients, two tumors were located with68Ga DOTATATE-PET/CT and one with OctreoScan. The causal tumors were located in the lower extremities in five patients and invading the frontal sinus in one patient. In all patients, tumors were successfully removed. Within 14 days, there was normalization of phosphate and FGF23 levels and resolution of clinical symptoms in all patients. In all cases, the histopathology was compatible with a phosphaturic mesenchymal tumor.



The clinical presentation, delay time to diagnosis, FGF23 diagnostic sensitivity and histopathology in this first series of South American patients is similar to those described in other populations. The success of localization by somatostatin analog-based imaging, suggests this may the optimal imaging modality.
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile.
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González
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile.
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Baudrand
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile.
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Sepúlveda
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile.
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Vucetich
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile.
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Guarda
Departamento de Neurocirugía, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Santiago, Chile.
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Villanueva
Departamento de Radiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Santiago, Chile.
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Contreras
Departamento de Traumatología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Santiago, Chile.
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Villa
Instituto de Ciencias Biomédicas, Hospital Clinico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile.|Centro de Investigacion Clinica Avanzada, Hospital Clinico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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Salech
Instituto de Ciencias Biomédicas, Hospital Clinico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile.|Centro de Investigacion Clinica Avanzada, Hospital Clinico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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Toro
Instituto de Ciencias Biomédicas, Hospital Clinico Universidad de Chile, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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Michea
Departamento de Endocrinología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, Cuarto piso, Santiago, Chile. pflorenz@uc.cl.
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http://orcid.org/0000-0001-5936-3146
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Florenzano
D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood; D001859:Bone Neoplasms / Q000150:complications / Q000175:diagnosis / Q000601:surgery; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D005598:Fractures, Spontaneous / Q000000981:diagnostic imaging / Q000209:etiology; D006801:Humans; D017674:Hypophosphatemia / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009372:Neoplasms, Connective Tissue / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D015282:Octreotide / Q000031:analogs & derivatives; D009942:Organometallic Compounds; D010018:Osteomalacia; D010257:Paraneoplastic Syndromes / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000150:complications / Q000175:diagnosis / Q000601:surgery; D055815:Young Adult
D014408:Biomarkers, Tumor; C000717427:FGF23 protein, human; C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D015282:Octreotide
68Ga PET/CT; FGF23; Hypophosphatemia; Osteomalacia; Tumor-induced osteomalacia