Tumor-induced osteomalacia: An important cause of adult-onset hypophosphatemic osteomalacia in China: Report of 39 cases and review of the literature

Abstract

Tumor-induced osteomalacia (TIO) is an acquired form of hypophosphatemia. Tumor resection leads to cure. We investigated the clinical characteristics of TIO, diagnostic methods, and course after tumor resection in Beijing, China, and compared them with 269 previous published reports of TIO. A total of 94 patients with adult-onset hypophosphatemic osteomalacia were seen over a 6-year period (January, 2004 to May, 2010 in Peking Union Medical College Hospital. After physical examination (PE), all patients underwent technetium-99m octreotide scintigraphy ( 99 Tc m -OCT). Tumors were removed after localization. The results demonstrated that 46 of 94 hypophosphatemic osteomalacia patients had high uptake in 99 Tc m -OCT imaging. Forty of them underwent tumor resection with the TIO diagnosis established in 37 patients. In 2 patients, the tumor was discovered on PE but not by 99 Tc m -OCT. The gender distribution was equal (M/F ¼ 19/20). Average age was 42 AE 14 years. In 35 patients (90%), the serum phosphorus concentration returned to normal in 5.5 AE 3.0 days after tumor resection. Most of the tumors (85%) were classified as phosphaturic mesenchymal tumor (PMT) or mixed connective tissue variant (PMTMCT). Recurrence of disease was suggested in 3 patients (9%). When combined with the 269 cases reported in the literature, the mean age and sex distribution were similar. The tumors were of bone (40%) and soft tissue (55%) origins, with 42% of the tumors being found in the lower extremities. In summary, TIO is an important cause of adult-onset hypophosphatemia in China. 99 Tc m -OCT imaging successfully localized the tumor in the overwhelming majority of patients. Successful removal of tumors leads to cure in most cases, but recurrence should be sought by long-term follow-up. ß

Nationwide survey of fibroblast growth factor 23 (FGF23)-related hypophosphatemic diseases in Japan: prevalence, biochemical data and treatment

“…We also obtained the biochemical data of 7 adults, 4 children and 1 infant who already had been treated with active vitamin D 3 and/or phosphate at baseline. Their treat- affected [8]. Our data indicate almost the same epidemiological results.…”

FGF23 and Phosphate Wasting Disorders

“…A stepwise approach, first performing functional tests and then anatomical tests, is advocated. In our hospital, we have successfully used 99Tcm-OCT scintigraphy to locate tumors in most patients with TIO as we previously reported (94). Therefore, we prefer octreotide scintigraphy as the first approach.…”

“…Tumor resection is almost always curative, and following complete resection of the tumor, there is relatively rapid improvement. FGF23 disappears rapidly from the circulation (99) and serum phosphate returns to normal within five days post operation (94). Most patients feel better within days to weeks of tumor removal.…”

“…Removal of the tumor is associated with reduction in serum FGF23 concentrations, and there is a temporal association between the reduction in FGF23 concentration and the elevation in serum phosphate, decrease in renal phosphate wasting, and increase in 1,25(OH)2D3 concentrations (93)(94). The diagnosis of TIO can be challenging because the tumors are often small and difficult to find.…”

Glomus tumor as a cause of oncogenic osteomalacia

“…As mentioned before mesenchymal tumor is the most common etiology for tumor induce osteomalacia. Hemangiopericytoma is the most common type though the other more prevalent tumors are fibrous dysplasia, osteosarcoma, chondroblastoma, chondromyxoid fibroma, malignant fibrous histiocytoma, giant cell tumor, haemangioma, paraganglioma, prostate cancer and oat cell carcinoma of the lung, and these tumors occasionally are too small in size that is difficult for detection (4). Imaging in oncogenic osteomalacia for detecting the primary site of tumor is very important, because the localization of primary tumor is very difficult.…”