Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Department of Pathology, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
J Orthop Sci. 2021 Sep;26(5):870-877. doi: 10.1016/j.jos.2020.07.006. Epub 2020 Aug 11.
Phosphaturic mesenchymal tumors primarily cause tumor-induced osteomalacia, a rare paraneoplastic syndrome, and half occur in soft tissues. There are few reports about the surgical margins of these tumors. This study aimed to clarify the optimal surgical margin for phosphaturic mesenchymal tumors by analyzing radiological and histopathological features.
This study included eight cases, seven primary and one recurrent, of tumor-induced osteomalacia caused by soft-tissue phosphaturic mesenchymal tumors that were surgically treated between January 2000 and January 2019. We evaluated the radiological and histopathological features of all tumors and investigated the correlation of these features, the surgical margin, and recurrence of hypophosphatemia.
The tumors were located in superficial (n = 5) and deep (n = 3) tissues. Six of the eight tumors had a clear boundary, but five had an irregular margin. Three tumors had a hypointense rim on T2-weighted images, indicating fibrous tumor encapsulation. Histopathological analysis revealed infiltrative growth in six of the eight tumors, which correlated with an irregular margin seen on imaging. Although there was no recurrence in patients treated with an intended wide margin >1 cm, one of the three patients treated with marginal tumor resection experienced a recurrence of hypophosphatemia, with histopathological analysis showing infiltration of subcutaneous fat. In contrast, two tumors with clear boundaries, regular margins, and fibrous capsule seen on imaging, had no infiltrative growth and were cured by marginal resection. In one recurrent case, tumor infiltration was observed in the previous surgical scar, which was not detected on preoperative imaging.
Soft-tissue phosphaturic mesenchymal tumors with an irregular boundary seen on imaging tend to be infiltrative, especially into subcutaneous fat, and should be treated by at least a 1-cm wide margin resection. Tumors with a fibrous capsule with clear and regular margins are cured by marginal margin resection. These findings could inform surgeons' decisions regarding the resection of soft-tissue phosphaturic mesenchymal tumors.
磷状基质肿瘤主要引起肿瘤诱导性骨软化症，这是一种罕见的副瘤综合征，其中一半发生在软组织中。关于这些肿瘤的手术切缘，报道较少。本研究旨在通过分析影像学和组织病理学特征，明确磷状基质肿瘤的最佳手术切缘。
本研究纳入了 2000 年 1 月至 2019 年 1 月期间手术治疗的 7 例原发性和 1 例复发性软组织磷状基质肿瘤引起的肿瘤诱导性骨软化症患者，共 8 例。我们评估了所有肿瘤的影像学和组织病理学特征，并探讨了这些特征与手术切缘和低磷血症复发的相关性。
肿瘤位于表浅组织（n=5）和深部组织（n=3）。8 例肿瘤中，6 例有清晰边界，但 5 例有不规则边界。3 例肿瘤在 T2 加权图像上有低信号环，提示纤维性肿瘤包膜。组织病理学分析显示，8 例肿瘤中有 6 例呈浸润性生长，这与影像学上的不规则边界相关。尽管在接受大于 1cm 广泛切缘治疗的患者中没有复发，但在接受边缘肿瘤切除治疗的 3 例患者中有 1 例出现低磷血症复发，组织病理学分析显示皮下脂肪浸润。相比之下，2 例在影像学上边界清晰、边缘规则且有纤维包膜的肿瘤无浸润性生长，仅行边缘切除即可治愈。在 1 例复发病例中，术中发现肿瘤浸润到术前影像学未检测到的先前手术疤痕中。
影像学上边界不规则的软组织磷状基质肿瘤往往具有浸润性，特别是浸润到皮下脂肪，应至少行 1cm 宽的边缘切除。有纤维包膜、边界清晰且规则的肿瘤可通过边缘切除治愈。这些发现可为外科医生决定切除软组织磷状基质肿瘤提供依据。
