Abstract:

Objective One case of intracranial phosphaturic mesenchymal tumor (PMT) was reported to study the clinicopathologic characteristics, immunohistochemical features, differential diagnosis and prognosis of PMT. Methods and Results A 53-year-old man presented with 7 years history of bone pain with hypophosphatemia, aggravated for one month. A tumor was discovered in left occipital bone by ⁹⁹Tc^m-octreotide scanning. MRI showed left occipital bone and duramater masses. Tumor-induced osteomalacia (TIO) was diagnosed and the lesion was completely removed. The lesions meningeal tissue, periosteum and left occipital bone were examined pathologically. The microscopiy showed that the tumor growed diffusely, involving meningges and bones, and mainly composed of oval and short spindle cells. It contains malformed thick-walled vessels, dilated sinusoidal vessels, mature adipose tissue, interstitial mucinous degeneration and mitosis without typical mitotic activity and necrosis. Immunohistochemically, the tumor cells were positive for fibroblast growth factor-23 (FGF-23), Vimentin (Vim), somatostatin receptor 2 (SSTR2), CD56 and neuron-specific enolase (NSE), and focal expression of Bcl-2, D2-40; the Ki-67 labeling index was 5%. Pathological diagnosis was PMT. The patient's serum phosphate level returned to normal after operation. The case had followed-up for 22 months, and survived with normal phosphatemia and without local recurrence and distant metastasis at the last followed-up. Conclusions Intracranial PMT is very rare, and it is very difficult to detect the lesion early. The differential diagnosis should be considered with meningioma and hemangiopericytoma. Accurate localization and completely excision of tumor are effective therapeutic methods. Clinical features, blood biochemical characteristics, image localization and immunohistochemical phenotype are helpful for the correct diagnosis and identification of the spindle cell tumors such as meningoma.

Key words: Phosphaturic mesenchymal tumor (not in MeSH), Osteomalacia, Meninges, Immunohistochemistry

摘要：

目的 报告1例颅内磷酸盐尿性间叶肿瘤病例，并总结磷酸盐尿性间叶肿瘤病理学、影像学以及诊断与治疗特点。方法与结果 男性患者，53岁。以全身多发性骨痛7年、加重1个月入院。临床表现为血清磷明显降低；⁹⁹Tc^m-奥曲肽显像以左侧枕部生长抑素受体高表达灶为特征性改变；MRI显示左侧枕骨和硬脑膜病变。拟诊肿瘤诱发骨软化症，手术全切除病变。术后组织学形态观察，肿瘤呈弥漫浸润生长，累及硬脑膜和颅骨骨质，肿瘤细胞呈卵圆形和短梭形，可见畸形厚壁血管、扩张的窦样血管、成熟脂肪组织和间质黏液变性，核分裂象罕见，未见坏死。免疫组织化学染色，肿瘤细胞胞质高表达纤维母细胞生长因子-23、波形蛋白、生长抑素受体2、CD56和神经元特异性烯醇化酶，灶性表达Bcl-2和D2-40，Ki-67抗原标记指数为5%。病理诊断：磷酸盐尿性间叶肿瘤。术后血清磷恢复正常，随访22个月肿瘤无复发、无转移。结论 颅内磷酸盐尿性间叶肿瘤极其罕见，病变隐匿而不易早期发现，常被误诊为脑膜瘤和血管外皮瘤，准确定位并全切除肿瘤是有效治疗方法。综合临床表现、血液生化、影像学和病理学特点有助于准确诊断并与脑膜瘤等梭形细胞肿瘤相鉴别。

关键词: 磷酸盐尿性间叶肿瘤(非MeSH词), 骨软化症, 脑膜, 免疫组织化学