Primary CNS vasculitis (PCNSV) is uncommonly considered in the differential diagnosis of tumor-like lesions. This case report of tumefactive PCNSV highlights imaging features that should increase clinical suspicion for CNS vasculitis, potentially lending to earlier diagnosis and treatment. A 62-year-old man presented with a 1-month history of focal motor seizures and cortical sensory loss localizing to the right frontoparietal lobe. Noncontrast head CT was suggestive of glioma, resulting in intravenous dexamethasone administration and admission to neurosurgery. MRI appearance was atypical for glioma, with relative preservation of regional anatomy, intralesional microhemorrhage, and patchy peripheral enhancement. Despite normal CT angiogram, CSF, and serum inflammatory markers, brain biopsy was suggestive of lymphocytic vasculitis. Extensive workup for secondary causes was negative, and he was diagnosed with tumefactive PCNSV. Treatment with corticosteroids and cyclophosphamide resulted in sustained clinical and radiologic improvement. Tumefactive PCNSV is an angiogram-negative small-vessel vasculitis that has a lymphocytic histologic pattern. Tumefactive PCNSV constitutes over 10% of PCNSV cases and can be recognized by the presence of intralesional microhemorrhages, absence of diffusion restriction, and a patchy or nodular enhancement pattern. The most important mimicker is CNS lymphoma, which has a similar imaging and histologic pattern. If individuals with tumefactive PCNSV do not have a sustained immunotherapy response, repeat biopsy should be promptly performed.

中文翻译：

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珍珠和牡蛎：继发于原发性中枢神经系统血管炎的肿瘤样肿块病变。


原发性中枢神经系统血管炎 (PCNSV) 在肿瘤样病变的鉴别诊断中很少被考虑。这份肿胀性 PCNSV 病例报告强调了影像学特征，这些特征应增加临床对中枢神经系统血管炎的怀疑，可能有助于早期诊断和治疗。一名 62 岁男性，有 1 个月的局灶性运动癫痫病史和局限于右额顶叶的皮质感觉丧失。头部平扫 CT 提示神经胶质瘤，导致静脉注射地塞米松并入院神经外科。神经胶质瘤的 MRI 表现不典型，区域解剖结构相对保留，病灶内微出血和斑片状周边强化。尽管 CT 血管造影、脑脊液和血清炎症标志物正常，但脑活检提示淋巴细胞性血管炎。对次要原因进行的广泛检查结果呈阴性，他被诊断患有肿胀性 PCNSV。皮质类固醇和环磷酰胺治疗导致临床和放射学持续改善。肿瘤性 PCNSV 是一种血管造影阴性的小血管血管炎，具有淋巴细胞组织学模式。肿胀性 PCNSV 占 PCNSV 病例的 10% 以上，可通过病灶内微出血的存在、不存在扩散限制以及斑片状或结节状增强模式来识别。最重要的模仿者是中枢神经系统淋巴瘤，其具有相似的影像学和组织学模式。如果患有肿胀性 PCNSV 的个体没有持续的免疫治疗反应，应立即进行重复活检。