Song Claire, Chan Denise, Flaman Ashley, Kurien Elizabeth, Kline Gregory, Ghaznavi Sana
University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada.
Division of Radiology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada.
BMJ Case Rep. 2025 May 15;18(5):e265058. doi: 10.1136/bcr-2025-265058.
Tumour-induced osteomalacia (TIO) is a rare cause of acquired hypophosphataemia most often due to paraneoplastic overproduction of fibroblast growth factor-23 (FGF-23). A woman in her 60s presented with an 18 month history of insidious back, knee and ankle pain, and progressive weakness. Biochemistry revealed low serum phosphate and a bone scan showed diffuse bony lesions, initially suspected to be metastatic sarcoma given her history of uterine sarcoma. However, a positron emission tomography scan identified a solitary destructive lytic lesion in the right posterior second rib. Endocrine workup showed low serum phosphate, high fractional excretion of phosphate, normal 25-hydroxyvitamin D and elevated FGF-23 levels. A biopsy revealed spindle cell neoplasm, which later stained positive for FGF receptor 1, consistent with renal phosphate wasting secondary to TIO. The patient was started on burosumab, a human monoclonal antibody against FGF-23, which normalised her serum phosphate and led to marked clinical improvement. She is now awaiting curative surgery for the primary rib lesion.
肿瘤诱导的骨软化症（TIO）是获得性低磷血症的罕见病因，多数情况下是由于肿瘤旁分泌过量的成纤维细胞生长因子23（FGF-23）所致。一名60多岁的女性，有18个月隐匿性背痛、膝关节和踝关节疼痛病史，且病情逐渐加重。生化检查显示血清磷酸盐水平低，骨扫描显示弥漫性骨病变，鉴于其子宫肉瘤病史，最初怀疑是转移性肉瘤。然而，正电子发射断层扫描发现右后第二肋骨有一个孤立的破坏性溶骨性病变。内分泌检查显示血清磷酸盐水平低、磷酸盐排泄分数高、25-羟维生素D正常以及FGF-23水平升高。活检显示为梭形细胞瘤，后来FGF受体1染色呈阳性，符合TIO继发的肾性磷酸盐消耗。患者开始使用布罗索尤单抗，一种抗FGF-23的人单克隆抗体，该药物使她的血清磷酸盐水平恢复正常，并带来了显著的临床改善。她目前正在等待对原发性肋骨病变进行根治性手术。
