Kawai Shintaro, Ariyasu Hiroyuki, Furukawa Yasushi, Yamamoto Reika, Uraki Shinsuke, Takeshima Ken, Warigaya Kenji, Nakamoto Yuji, Akamizu Takashi
The First Department of Medicine.
Department of Human Pathology, Wakayama Medical University, WakayamaJapan.
Endocrinol Diabetes Metab Case Rep. 2017 Apr 19;2017. doi: 10.1530/EDM-17-0005. eCollection 2017.
Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by renal phosphate wasting leading to hypophosphatemia due to excessive actions of fibroblast growth factor 23 (FGF23) produced by the tumors. Although the best way of curing TIO is complete resection, it is usually difficult to detect the culprit tumors by general radiological modalities owing to the size and location of the tumors. We report a case of TIO in which the identification of the tumor by conventional imaging studies was difficult. Nonetheless, a diagnosis was made possible by effective use of multiple modalities. We initially suspected that the tumor existed in the right dorsal aspect of the scapula by Ga-DOTATOC positron emission tomography/computed tomography (Ga-DOTATOC-PET/CT) and supported the result by systemic venous sampling (SVS). The tumor could also be visualized by 3T-magnetic resonance imaging (MRI), although it was not detected by 1.5T-MRI, and eventually be resected completely. In cases of TIO, a stepwise approach of Ga-DOTATOC-PET/CT, SVS and 3T-MRI can be effective for confirmation of diagnosis.
TIO shows impaired bone metabolism due to excessive actions of FGF23 produced by the tumor. The causative tumors are seldom detected by physical examinations and conventional radiological modalities.In TIO cases, in which the localization of the culprit tumors is difficult, Ga-DOTATOC-PET/CT should be performed as a screening of localization and thereafter SVS should be conducted to support the result of the somatostatin receptor (SSTR) imaging leading to increased diagnosability.When the culprit tumors cannot be visualized by conventional imaging studies, using high-field MRI at 3T and comparing it to the opposite side are useful after the tumor site was determined.
肿瘤诱导的骨软化症（TIO）是一种罕见的副肿瘤综合征，其特征是肿瘤产生的成纤维细胞生长因子23（FGF23）作用过度导致肾脏磷酸盐流失，进而引起低磷血症。虽然治愈TIO的最佳方法是完全切除肿瘤，但由于肿瘤的大小和位置，通过常规放射学检查通常很难检测到罪魁祸首肿瘤。我们报告一例TIO病例，通过传统影像学检查难以识别肿瘤。尽管如此，通过有效使用多种检查方法得以确诊。我们最初通过镓标记的生长抑素受体拮抗剂（Ga-DOTATOC）正电子发射断层扫描/计算机断层扫描（Ga-DOTATOC-PET/CT）怀疑肿瘤存在于肩胛骨右背侧，并通过全身静脉采血（SVS）支持该结果。尽管1.5T磁共振成像（MRI）未检测到肿瘤，但该肿瘤也可通过3T磁共振成像（MRI）显示，最终被完全切除。在TIO病例中，采用Ga-DOTATOC-PET/CT、SVS和3T-MRI的逐步检查方法对确诊有效。
TIO因肿瘤产生的FGF23作用过度而导致骨代谢受损。通过体格检查和传统放射学检查很少能检测到致病肿瘤。在难以确定罪魁祸首肿瘤位置的TIO病例中，应进行Ga-DOTATOC-PET/CT作为定位筛查，然后进行SVS以支持生长抑素受体（SSTR）成像结果，从而提高诊断率。当通过传统影像学检查无法显示罪魁祸首肿瘤时，在确定肿瘤部位后，使用3T高场MRI并与对侧进行比较是有用的。
