Reports of 17 Chinese patients with tumor-induced osteomalacia

• Published in: Journal of bone and mineral metabolism Vol. 35; no. 3; pp. 298 - 307
• Main Authors: Yu, Wei-Jia, He, Jin-Wei, Fu, Wen-Zhen, Wang, Chun, Zhang, Zhen-Lin
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.05.2017; Springer Nature B.V
• Subjects: Adult; Aged; Alkaline Phosphatase - blood; Asian Continental Ancestry Group - genetics; China; Female; Fibroblast Growth Factors - blood; Follow-Up Studies; Humans; Magnetic Resonance Imaging; Male; Medicine; Medicine & Public Health; Metabolic Diseases; Middle Aged; Neoplasms, Connective Tissue - blood; Neoplasms, Connective Tissue - diagnostic imaging; Neoplasms, Connective Tissue - pathology; Neoplasms, Connective Tissue - surgery; Octreotide - analogs & derivatives; Octreotide - chemistry; Organotechnetium Compounds - chemistry; Original Article; Orthopedics; Phosphorus - blood; Positron Emission Tomography Computed Tomography; Young Adult; Tumor-induced osteomalacia; F-Fluorodeoxyglucose positron emission tomography and computed tomography; Fibroblast growth factor 23; 18F-Fluorodeoxyglucose positron emission tomography and computed tomography
• ISSN: 0914-8779; 1435-5604
• DOI: 10.1007/s00774-016-0756-9

Tumor-induced osteomalacia (TIO) is a rare acquired form of hypophosphatemic osteomalacia, which is usually attributed to the overproduction of fibroblast growth factor 23 (FGF-23) by benign mesenchymal neoplasms. Localization and thereafter surgical resection of tumors lead to a cure. The present study aimed to investigate the clinical data, diagnostic methods, and follow-up after tumor resection at one medical center in Shanghai to characterize the profile of this rare disorder and to share our successful experience in diagnosis and treatment. Twenty-three patients with adult-onset hypophosphatemia osteomalacia seen in Shanghai Sixth People’s Hospital from 2009 to 2014 and 95 normal individuals were enrolled. After taking a medical history and performing a physical examination, we analyzed the laboratory results (including the serum FGF-23 levels) and localized the tumors by 18 F-fluorodeoxyglucose positron emission tomography and computed tomography ( 18 F-FDG PET/CT), 99m Tc-octreotide ( 99m Tc-OCT) scintigraphy, and magnetic resonance imaging (MRI). On the basis of the results of laboratory tests and imaging findings, tumor resection was conducted in 17 patients with a certain diagnosis of TIO. The results demonstrated that the 17 patients (nine men and eight women, average age 46.6 ± 12.9 years) had TIO. FGF-23 level was elevated in 94.1 % of patients (16 of 17 patients) . Serum phosphorus level decreased in 100 % of patients. 18 F-FDG PET/CT revealed five tumors, 99m Tc-OCT scintigraphy revealed two tumors, physical examination revealed nine tumors, and MRI revealed one tumor, among which 58.8 % of the causative tumors (10 of 17 tumors) were located in the lower extremities. After tumor resection, serum phosphorus levels normalized in 100 % of patients (all 17 patients) in 4–21 days and FGF-23 levels decreased in 90 % of patients (nine of ten patients). We found 64.7 % of the tumors (11 of 17 tumors) were phosphaturic mesenchymal tumors or a phosphaturic mesenchymal tumor mixed connective tissue variant. Measurement of serum phosphorus and FGF-23 levels in patients with suspected TIO is of paramount importance for diagnosing of TIO. 18 F-FDG PET/CT, 99m Tc-OCT scintigraphy, and physical examination play a considerable role in revealing TIO-associated tumors. TIO-associated tumors were more frequently located in the lower extremities than in other places; thus, the lower extremities need to be carefully checked. Complete surgical resection results in normalization of parameters in laboratory tests and relief of symptoms of TIO patients.