磷酸盐尿性间叶肿瘤的临床特点及其综合影像学表现

目的 探讨磷酸盐尿性间叶肿瘤（PMT）的临床特点及其综合影像学表现。 方法 回顾性分析2014年3月至2018年11月于上海交通大学附属第六人民医院经组织病理学检查确诊的38例PMT患者（其中男性22例、女性16例，年龄8~72岁, 中位年龄45.5岁）的临床资料，以及超声、CT、MRI、99Tcm-联肼尼克酰胺-酪氨酸3-奥曲肽（99Tcm-HYNIC-TOC）SPECT/CT、99Tcm-亚甲基二膦酸盐（99Tcm-MDP）SPECT/CT骨显像和18F-氟脱氧葡萄糖（FDG）PET/CT的影像学表现，分析并总结PMT的临床特点及其综合影像学表现。 结果 PMT患者的临床症状主要表现为进行性全身骨痛、肌肉无力以及肿瘤原发部位局部不适等；术前患者的血液生化检查结果显示血磷水平降低。38例患者中，有超声、CT、MRI、99Tcm-HYNIC-TOC SPECT/CT、99Tcm-MDP SPECT/CT骨显像和18F-FDG PET/CT显像资料者分别为8、20、18、12、8、7例。PMT患者的超声图像表现为肿瘤内低或混合回声，血流信号丰富。50.0%（4/8）骨组织来源的PMT患者在CT上表现为溶骨性病变；软组织来源的12例PMT患者在CT上表现为异常软组织密度灶或软组织肿块。PMT患者的病灶在 MRI上均表现为T1加权像等低信号、T2加权像高低混杂信号，增强MRI表现为肿瘤实性部分明显强化。PMT患者99Tcm-HYNIC-TOC SPECT/CT显像阳性率为83.3%（10/12）。PMT患者99Tcm-MDP SPECT/CT骨显像均呈多发异常骨代谢活跃灶，其中1例软组织来源的肿瘤显示为病灶放射性摄取轻度增高。PMT患者18F-FDG PET/CT显像中所有病灶的葡萄糖代谢均增高，最大标准化摄取值为3.1~10.7，中位数为4.0。 结论 PMT的临床特点主要表现为肿瘤导致的低磷性骨软化，而原发肿瘤的表现不突出；影像学表现没有特异性，99Tcm-HYNIC-TOC SPECT/CT、99Tcm-MDP SPECT/CT骨显像及18F-FDG PET/CT检查可能有助于临床对PMT进行准确地定位并评估患者的全身情况。

Clinical features and comprehensive imaging findings of phosphaturic mesenchymal tumor

Objective To explore the clinical features and comprehensive imaging findings of phosphaturic mesenchymal tumor (PMT). Methods A total of 38 histopathologically proven patients with PMT (22 males and 16 females; age, 8–72 years; median age, 45.5 years) in the Sixth People's Hospital Affiliated to Shanghai Jiaotong University from March 2014 to November 2018 were included in this study. The relevant clinical data and ultrasound, CT, MRI, 99Tcm-hydrazinonicotinamide-Tyr3-octreotide (99Tcm-HYNIC-TOC) SPECT/CT, 99Tcm-methylenediphosphonate (99Tcm-MDP) SPECT/CT bone scan, and 18F-fluorodeoxyglucose (FDG) PET/CT imaging findings were retrospectively analyzed, and their comprehensive imaging findings and clinical features were summarized. Results The clinical manifestations of patients with PMT were mainly progressive systemic bone pain, muscle weakness, and local discomfort at the primary site of the tumor. All patients showed hypophosphatemia before operation. Of the 38 patients included, 8, 20, 18, 12, 8, and 7 patients respectively received ultrasound, CT, MRI, 99Tcm-HYNIC-TOC SPECT/CT, 99Tcm-MDP SPECT/CT bone scan, and 18F-FDG PET/CT. The ultrasonographic characteristics were low or mixed echoes and abundant color blood flow signals. Also, 50.0% (4/8) of the osseous PMT were osteolytic on CT, 12 soft tissue lesions were abnormal density focus or soft tissue mass on CT. All lesions presented low signal intensity on T1 weighted imaging and high or low signal intensity on T2 weighted imaging in 18 patients who underwent MRI, and tumor parenchyma was obviously enhanced. Ten of the 12 (83.3%) patients were positive on 99Tcm-HYNIC-TOC SPECT/CT imaging. 99Tcm-MDP SPECT/CT bone scan showed increased radiotracer uptake over the bone lesions, and one case of soft tissue lesion showed a slight increase in radiation uptake. On 18F-FDG PET/CT, all lesions showed intense FDG uptake with a median maximum standardized uptake value of 4.0 (range, 3.1–10.7). Conclusions The clinical feature of PMT is tumor-induced osteomalacia with hypophosphatemia. However, the symptoms of the primary tumor are not prominent. No specific imaging findings of PMT were noted. However, 99Tcm-HYNIC-TOC SPECT/CT, 99Tcm-MDP SPECT/CT bone scan, and 18F-FDG PET/CT may be helpful in tumor localization and whole-body assessment.