Tumor-induced osteomalacia

Abstract

Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare paraneoplastic syndrome characterized by hypophosphatemia resulting from decreased tubular phosphate reabsorption, with a low or inappropriately normal level of active vitamin D. The culprit tumors of TIO could produce fibroblast growth factor 23 which plays a role in regulating renal Pi handling and 25-hydroxyvitamin D 1α-hydroxylase activity. Chronic hypophosphatemia could eventually lead to inadequate bone mineralization, presenting as osteomalacia. The diagnosis should be considered when patients manifest as hypophosphatemia and osteomalacia, or rickets and needs to be differentiated from other disorders of phosphate metabolism, such as the inhereditary diseases like X-linked hypophosphataemic rickets, autosomal dominant hypophosphataemic rickets, autosomal recessive hypophosphataemic rickets and acquired diseases like vitamin D deficiency. Localization of responsible tumors could be rather difficult since the vast majority are very small and could be everywhere in the body. A combination of thorough physical examination, laboratory tests and imaging techniques should be applied and sometimes a venous sampling may come into handy. The technology of somatostatin-receptor functional scintigraphy markedly facilitates the localization of TIO tumor. Patients undergoing complete removal of the causative neoplasm generally have favorable prognoses while a few have been reported to suffer from recurrence and metastasis. For those undetectable or unresectable cases, phosphate supplements and active vitamin D should be administrated and curative intended radiotherapy or ablation is optional.

Detection Rate of Culprit Tumors Causing Osteomalacia Using Somatostatin Receptor PET/CT: Systematic Review and Meta-Analysis

“…Tumor-induced or oncogenic osteomalacia (TIO) is a rare paraneoplastic syndrome [1,2]. The majority of TIO cases are caused by phosphaturic mesenchymal tumors [3].…”

“…The culprit tumors of TIO produce fibroblast growth factor 23 (FGF23), a protein which regulates renal phosphate handling and 25-hydroxyvitamin D 1α-hydroxylase activity. The hypersecretion of FDG-23 may cause hypophosphatemia due to a decreased tubular phosphate reabsorption and a low level of active vitamin D. Chronic hypophosphatemia could eventually lead to inadequate bone mineralization, presenting as osteomalacia [1,2].…”

“…Due to its nonspecific clinical presentation or lack of awareness, the diagnosis of TIO is often significantly delayed, resulting in physical suffering or psychological distress for the patients. The diagnosis of TIO should be considered in patients with hypophosphatemia and osteomalacia-or rickets-but a differential diagnosis from other disorders of phosphate metabolism should be undertaken [1,2].…”

“…The accurate and early detection and localization of culprit tumors in patients with TIO is crucial for patient management and treatment. The successful detection and complete surgical resection of the culprit tumors typically leads to the rapid resolution of symptoms or the reversal of biochemical imbalance [1]. The detection of culprit tumors in patients with TIO may be challenging, since the majority of these tumors are very small and can be localized everywhere in the body.…”

Multidisciplinary patient care in X‐linked hypophosphatemic rickets: one challenge, many perspectives

“…Tumour-induced osteomalacia (TIO) Fig. 2 Accurate preoperative deformity analysis allows an optimizes surgical treatment approach in patients with X-linked hypophosphatemic rickets is caused mainly by mesenchymal tumours and is associated with low phosphate levels due to paraneoplastic FGF23 overproduction [26]. In general, TIO is curable if the tumour can be removed [27].…”