title: Tumor-induced rickets in a child with a central giant cell granuloma: a case report.
abstract: Tumor-induced osteomalacia/rickets is a rare paraneoplastic disorder associated with a tumor-producing fibroblast growth factor 23 (FGF23). We present a child with symptoms of rickets as the first clinical sign of a central giant cell granuloma (CGCG) with high serum levels of FGF23, a hormone associated with decreased phosphate resorption. A 3-year-old boy presented with a limp and 6 months later with painless growth of the jaw. On examination gingival hypertrophy and genu varum were observed. Investigations revealed hypophosphatemia, normal 1,25 and 25 (OH) vitamin D, and high alkaline phosphatase. An MRI showed an osteolytic lesion of the maxilla. Radiographs revealed typical rachitic findings. Incisional biopsy of the tumor revealed a CGCG with mesenchymal matrix. The CGCG was initially treated with calcitonin, but the lesions continued to grow, making it necessary to perform tracheostomy and gastrostomy. One year after onset the hyperphosphaturia worsened, necessitating increasing oral phosphate supplements up to 100 mg/kg per day of elemental phosphorus. FGF23 levels were extremely high. Total removal of the tumor was impossible, and partial reduction was achieved after percutaneous computed tomography-guided radiofrequency, local instillation of triamcinolone, and oral propranolol. Compassionate use of cinacalcet was unsuccessful in preventing phosphaturia. The tumor slowly regressed after the third year of disease; phosphaturia improved, allowing the tapering of phosphate supplements, and FGF23 levels normalized. Tumor-induced osteomalacia/rickets is uncommon in children and is challenging for physicians to diagnose. It should be suspected in patients with intractable osteomalacia or rickets. A tumor should be ruled out if FGF23 levels are high.
authors.affiliation: Departments of Pediatrics, elisafcooke@gmail.com.
authors.forename: Elisa
authors.initials: E
authors.lastname: Fernández-Cooke
authors.affiliation: Departments of Pediatrics.
authors.forename: Jaime
authors.initials: J
authors.lastname: Cruz-Rojo
authors.affiliation: Radiology, Division of Pediatrics, and.
authors.forename: Carmen
authors.initials: C
authors.lastname: Gallego
authors.affiliation: Oral & Maxillofacial Surgery, Division of Pediatrics, Hospital Universitario 12 de Octubre, Madrid, Spain; and.
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: Romance
authors.affiliation: Departments of Pediatrics.
authors.forename: Rocio
authors.initials: R
authors.lastname: Mosqueda-Peña
authors.affiliation: Lipid and Atherosclerosis Unit, IMIBIC/Reina Sofia University Hospital/University of Cordoba, and CIBER Fisiopatologia Obesidad y Nutricion, Instituto de Salud Carlos III, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Almaden
authors.affiliation: Departments of Pediatrics.
authors.forename: Jaime
authors.initials: J
authors.lastname: Sánchez del Pozo
mesh_terms: D001859:Bone Neoplasms / Q000150:complications*; D002675:Child, Preschool; D000089703:Fibroblast Growth Factor-23; D006101:Granuloma, Giant Cell / Q000150:complications*; D006801:Humans; D008297:Male; D009372:Neoplasms, Connective Tissue / Q000209:etiology*; D010018:Osteomalacia; D010257:Paraneoplastic Syndromes; D012279:Rickets / Q000209:etiology*