Primary angiitis of the central nervous system (PACNS) is a rare disease, and tumor-like primary angiitis of the central nervous system is even rarer. Histopathology is the gold standard for tumor-mimicking PACNS. However, pathological diagnosis is relatively limited due to fewer biopsy opportunities. A 68-year-old male presented with ataxia, and was diagnosed with tumor-like primary angiitis of the central nervous system. The patient underwent Intravenous drip glucocorticoid therapy (10 mg of dexamethasone, daily). After 10 days, the symptoms of the patient were completely relieved. Radiology revealed that the low density lesion in the right cerebellar hemisphere obviously narrowed. Cyclophosphamide therapy was not initiated. It is crucial for clinicians to be aware of changes in radiology that indicate PACNS, since the diagnosis of tumor-like PACNS remains quite challenging. Glucocorticoid therapy is an effective therapy in this condition, and the prognosis can be favorable.

中文翻译：

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共济失调是中枢神经系统肿瘤样原发性血管炎的主要表现：一例病例并文献复习

中枢神经系统原发性血管炎（PACNS）是一种罕见的疾病，中枢神经系统肿瘤样原发性血管炎更为罕见。组织病理学是模仿肿瘤的PACNS的金标准。然而，由于较少的活检机会，病理学诊断相对有限。一名68岁的男性表现为共济失调，并被诊断患有中枢神经系统的肿瘤样原发性血管炎。患者接受静脉滴注糖皮质激素治疗（每天10 mg地塞米松）。10天后，患者的症状完全缓解。放射学检查发现右小脑半球的低密度病变明显缩小。尚未开始使用环磷酰胺治疗。对于临床医生而言，了解指示PACNS的放射学变化至关重要，因为肿瘤样PACNS的诊断仍然颇具挑战性。在这种情况下，糖皮质激素治疗是一种有效的治疗方法，预后良好。