原发性中枢神经系统淋巴瘤的不典型MRI表现

Atypical MRI manifestations of primary central nervous system lymphoma

目的尽管已有文献对PCNSL的影像特点进行了描述,但对于不典型影像表现的患者依然存在一定比例的误诊。本研究旨在描述PCNSL患者的不典型磁共振成像(MRI)特点。方法纳入36例在本院经活检确诊为PCNSL的患者,并对影像特点进行回顾性分析。结果 36例患者(男∶女=17∶19,9~72岁)中共发现有99处脑部病变。24例(66.7%)为单发病灶,其余12例(33.3%)为多发性病灶,其中6例(16.7%)为2个病灶、2例(5.6%)为3个病灶、4例(11.1%)为3个以上病灶,病灶最多的一例患者有21个病灶。19例患者(52%)因MRI表现不典型,术前诊断为转移性肿瘤或炎症性疾病。不典型MRI表现形式包括:(1)占位病灶位置(脑室内、颅底、软脑膜、松果体);(2)病灶周围无水肿;(3)DWI低信号;(4)病灶中心坏死、出血改变;(5)不典型的强化形式:不均匀强化、环形强化、开环状强化、强化病灶中心更高信号的点状或线状强化区;(6)序列MRI提示病灶改变:病灶自发性消失或缩小,短期内病灶明显增大、增多、融合。结论 PCNSL具有多种MRI表现。PCNSL患者中具有不典型MRI表现的占有一定比例,甚至类似其他疾病如炎症、感染性疾病和颅内肿瘤。

Objective Primary central nervous system lymphoma（ PCNSL） is a malignant lymphoma confining to the central nervous system. Although imaging characteristics of PCNSL have been described,there still exists misdiagnosis in a proportion of patients presenting with atypical manifestations. In this study,we aim to describe the atypical magnetic resonance imaging（ MRI） features of PCNSL. Methods 36 patients diagnosed as PCNSL by biopsy in our hospital were included and analyzed retrospectively. Results 99 brain lesions were found in 36 patients（ male ∶ female = 17 ∶ 19,9 to 72 years old）. All of these patients were immunocompetent except one girl who had undergone renal transplantation and immunosuppression therapy. Twenty-four of them（ 66.7%） had single lesion,whereas 12 of them（ 33.3%） had multifocal lesions. In multifocal lesions group,the number of lesions varied from 2 to 21. Nineteen patients（ 52%） had atypical MRI features that were diagnosed with other tumor or inflammatory disease before biopsy or surgery. The atypical MRI features in our series included： 1. Atypical lesions location（ isolated intra-vantricular,skull base,leptomeninges,pineal body）; 2. No peri-lesion edema; 3. Low DWI signal; 4. Necrosis or hemorrhage with lesions; 5. Atypical enhancing characteristics（ heterogenic,rim,open ring enhancement; dot or linear higher enhanced signal within a enhanced lesion background）; 6. Morphology change in sequential MRI（ lesions diminished or vanished spontaneously,lesions multiplied,enlarged and fused in short intervals）. Conclusions PCNSL has variable MRI presentations.A proportion of PCNSL patients present with atypical MRI features and even mimic other diseases including inflammation,infection and other brain tumors. The characteristics of MRI with contrast enhancement may imply the progression of PCNSL.