小脑脑桥角区恶性周围神经鞘瘤的临床和病理学特征分析

Analysis of clinical and pathological features of malignant peripheral nerve sheath tumors in cerebellopontine angle

目的探讨小脑脑桥角区(CPA)恶性周围神经鞘瘤(MPNST)患者的临床、影像学及病理学特征。方法回顾性纳入首都医科大学附属北京天坛医院神经外科2013年3月至2018年3月收治的经病理学确诊的CPA区MPNST患者,共8例(占同期CPA病变的0.2%,3/3 500);另外纳入38例散发神经鞘瘤患者为对照组。分别比较两组患者的临床、影像学及病理学特征。结果8例MPNST患者中,男1例,女7例;诊断年龄为26~60(42.1 ± 13.4)岁;病程为1~18个月(中位数为6个月),与对照组的3~120个月(中位数为24个月)比较,差异有统计学意义(P=0.009)。与对照组比较,MPNST组患者术前更容易出现颅高压症状[分别为4/8、4/38(10.5%),P=0.022]、听力丧失[分别为8/8、14 /38(36.8%),P=0.001]及面神经功能丧失[分别为3/8、1/38(2.6%),P=0.013];肿瘤全切除比例[分别为4/8、37/38(97.4%),P=0.002]及术后面神经保留比例[分别为4/8、38/38(100.0%),P<0.001]均低于对照组。两组患者肿瘤体积、囊变等影像学特征比较差异均无统计学意义。组织病理学比较,MPNST组有坏死区域(分别为2/8、0/38,P=0.027),核分裂象[分别为(38.0±4.2)个/10 HPF、(1.9±1.0)个/10 HPF]、Ki-67[分别为(14.2± 8.7)%、(1.9 ± 1.0)%]和p53阳性表达(分别为4/8、0/38)均高于对照组,差异均有统计学意义(均P<0.001);两组患者S100、Vimentin表达均为阳性。在3例MPNST样本中,均未检测到NF2基因突变;而30例神经鞘瘤样本中共检测出18例(60.0%)存在NF2基因突变。8例MPNST患者随访时间为12~41个月,平均(22.4±7.4)个月。复发4例,平均复发时间为(11.8 ±3.7)个月;2例死亡。结论CPA区的MPNST极为罕见,影像学很难与神经鞘瘤区别,该肿瘤具有高度恶性的临床及组织病理学特征,组织病理学为主要的确诊方法。

Objective To analyze the clinical and pathological features of malignant peripheral nerve sheath tumors (MPNSTs) located in cerebellopontine angle (CPA). Methods Eight patients of MPNSTs in CPA region admitted to Department of Neurosurgery of Beijing Tiantan Hospital, Capital Medical University between March 2013 and March 2018 were retrospectively included, and 38 patients with sporadic schwannoma (VS) were enrolled as control. T test and Fisher test were used to compare the differences in clinical factors, imaging findings and pathologic characteristics between MPNST group and control. Results This study invlved 8 cases of CPA MPNST (1 male and 7 female). The age of patients with MPNST at diagnosis was 26-60 years (42.1±13.4 years) old. The disease duration with MPNST was 1-18 months (median: 6 months), compared with 3-120 months (median: 24 months) in the control, and the difference was statistically significant (P=0.009). The incidence rates of preoperative hearing loss (8/8 vs. 14 /38, P=0.001), facial nerve dysfunction (3/8 vs. 1/38, P=0.013), cranial hypertension symptoms (4/8 vs. 4/38, P=0.022), the proportion of total tumor resection (4/8 vs. 37/38, P=0.002) and the proportion of facial nerve preservation after surgery (4/8 vs. 38/38, P<0.001) were higher in MPNST patients than in those with sporadic VS, respectively. MPNSTs displayed higher mitotic activity [(38.0 ± 4.2)/10 HPF vs.(1.9 ± 1.0)/10 HPF] and Ki-67 index [(14.2± 8.7)% vs.(1.9 ± 1.0%)] than VS, respectively (both P<0.001). Nuclear positivity of p53 was also higher in MPNST than in VS (4/8 vs. 0/38, P<0.001). In addition, NF2 gene mutation was found in 18 of 30 (60.0%) cases of VS, while none of 3 cases of MPNST was detected with NF2 mutation.All of the MPNST patients were followed up for 12-41 months (22.4±7.4 months), recurrence occurred in 4 patients (average recurrence time: 11.8±3.7 months) and 2 cases of MPNST patients died. Conclusions MPNSTs in CPA are extremely rare and imaging is difficult to distinguish it from VS. MPNSTs show highly malignant clinical and pathohistological features and histopathology is the main method of diagnosis.