这是一个独特的病例，描述了一位原本健康并具备免疫力的患者中罕见的致命性、克隆性CD8阳性T细胞淋巴增生性疾病的表现、调查和疾病进展。涉及中枢神经系统的T细胞淋巴增生性疾病罕见，通常出现在免疫抑制状态下。这些疾病常与侵袭性细胞形态特征和特殊的磁共振成像模式相关，而此案未见这些特征。 本文描述了一位65岁男性患者的病例，其主要表现为神经精神症状、躯干共济失调和跌倒，其骨髓、脑脊液和脑活检均显示与克隆性CD8阳性T细胞淋巴增生性疾病一致，但不符合现有世界卫生组织对T细胞淋巴瘤分类的标准。患者接受了脑脊液腔内注射甲氨蝶呤治疗，症状短暂缓解后疾病进展，并因误吸导致死亡。 该病例凸显了对于中枢神经系统受累淋巴瘤临床特征提示的患者进行紧急和全面的检查的重要性，尽管其成像特征不典型且缺乏满足现行世界卫生组织分类标准的细胞形态特征。© 2023. BioMed Central Ltd., part of Springer Nature.

This is a unique case that describes the presentation, investigations, and disease trajectory of a fatal, clonal CD8-positive T-cell lymphoproliferative disorder in an otherwise healthy and immunocompetent patient with Epstein-Barr virus seronegative status. Central nervous system involving T-cell lymphoproliferative disorders are rare and typically encountered in the setting of immunocompromise. These disorders are often associated with aggressive cytomorphological features and characteristic magnetic resonance imaging patterns, which were not seen in this case.Here we describe a case of a 65 year-old male presenting with neuropsychiatric symptoms, truncal ataxia, and falls who's bone marrow, cerebrospinal fluid, and brain biopsy were consistent with a clonal CD8-positive T-cell lymphoproliferative disorder that did not meet existing World Health Organization criteria for classification as T-cell lymphoma. The patient was treated with intrathecal methotrexate resulting in transient improvement of his symptoms followed by disease progression and death related to aspiration.This case highlights the importance of urgent and comprehensive work-up in patients with clinical features suggestive of lymphoma with central nervous system involvement, despite atypical imaging features and lack of cytomorphological features satisfying current World Health Organization classification criteria.© 2023. BioMed Central Ltd., part of Springer Nature.