幕下非中线髓母细胞瘤的MRI表现及误诊分析

MRI Findings and Misdiagnosis of Infratentorial Non-midline Medulloblastoma

目的 探讨幕下非中线髓母细胞瘤(MB)的MRI特点,分析误诊原因。资料与方法 回顾性分析2014年1月—2021年1月定西市第二人民医院、吉林大学第一医院及中国人民解放军联勤保障部队第九二六医院经病理证实的9例幕下非中线MB的临床及MRI资料,总结其MRI特点,并分析误诊原因。结果 9例患者年龄19~36岁,平均(26.3±5.8)岁,男6例,女3例。9例均为幕下单发病灶,2例位于桥小脑角区,7例位于小脑半球表面,呈半圆形、类圆形或分叶状实性肿块,病灶内部均见囊状、条状小囊变区。瘤体T1WI呈低信号,T2WI呈稍高信号,T2 FLAIR以等信号为主,DWI呈高或稍高信号,表观扩散系数图呈低信号,表观扩散系数为(0.594±0.011)×10^(-3)mm^(2)/s,增强呈轻中度或不均匀明显强化;9例瘤周见水肿带。9例术前均误诊,其中4例误诊为脑膜瘤,1例误诊为神经鞘瘤,3例误诊为淋巴瘤,1例误诊为星形细胞瘤。结论 幕下非中线MB多发生于青年,MRI表现与典型MB不同,认识其发病年龄、发病部位和MRI特点有助于鉴别诊断。

Purpose To explore the MRI features of infratentorial non-midline medulloblastoma(MB), and to analyze the misdiagnosis reasons. Materials and Methods Nine patients were retrospectively enrolled, and the clinical and MRI data of infratentorial non-midline MB confirmed by pathology in Dingxi People’s Hospital, the First Hospital of Jilin University and the 926 Hospital of PLA from January 2014 to January 2021 were further analyzed, summarizing MRI characteristic and analyzing the misdiagnosis reasons. Results There were 9 patients aged 19 to 36(26.3±5.8) years old, and there were 6 males and 3 females. All 9 cases were infratentorial solitary lesions, including 2 lesions located in the cerebellopontine angle and 7 lesions located on the surface of the cerebellopontine angle. All lesions showed the semicircular, quasi-round or lobulated solid mass with cystic and strip cystic regions. The tumor showed hypointensity on T1WI, slightly hyperintense on T2WI, principal isointense signal on T2 FLAIR, high or slightly hyperintense on DWI, and hypointensity on ADC map. The average ADC value was(0.594±0.011)×10^(-3)mm^(2)/s. In addition, all lesions showed mild to moderate or inhomogeneous enhancements.Peritumoral edema zone was presented in 9 cases. Before operation, 9 cases were all misdiagnosed, including 4 cases misdiagnosed as meningioma, 1 case misdiagnosed as schwannoma, 3 cases misdiagnosed as lymphoma, 1 case misdiagnosed as astrocytoma. Conclusion Infatentorial non-midline MB mostly occurs in young people. MRI findings are different from typical MB. Understanding the age of onset,location and MRI characteristics of MB could be helpful for its differential diagnosis.