这里我们描述一位69岁男性的病例，他在67岁时体检时发现有中度血小板减少和严重脾肿大。第一次就诊时，他的白细胞（WBC）计数为7,400/μl 80% 淋巴细胞，骨髓穿刺显示 24% 异型淋巴细胞。非典型淋巴细胞的流式细胞术显示成熟T细胞标记物呈阳性，并且通过T细胞受体基因重排揭示了T细胞克隆性。 TCL1 免疫组织化学呈阴性。我们诊断出 TCL1 家族阴性 T 细胞幼淋巴细胞白血病 (T-PLL)，并采取观察等待。诊断后三十个月，尽管白细胞计数正常，患者仍出现尿潴留和右下肢麻痹，并检测到胸椎周围硬膜外肿瘤和脊髓受压。肿瘤被诊断为TCL1家族阴性T-PLL结外受累，但患者的全身状况迅速恶化，无法进行治疗。 T-PLL是一种以白细胞增多为特征的罕见疾病，白细胞计数通常随着疾病进展而增加。尽管建议通过血细胞计数进行观察，但重要的是要记住，即使血细胞计数没有变化，疾病也可能恶化。

Here we describe the case of a 69-year-old man who was found to have moderate thrombocytopenia and severe splenomegaly during a medical checkup at the age of 67. At the first visit, his white blood cell (WBC) count was 7,400/µl with 80% lymphocytes, and bone marrow aspiration showed 24% atypical lymphocytes. Flow cytometry of atypical lymphocytes was positive for mature T-cell markers, and T-cell clonality was revealed by T-cell receptor gene rearrangement. TCL1 was negative on immunohistochemistry. We diagnosed TCL1-family negative T-cell prolymphocytic leukemia (T-PLL) and employed watchful waiting. Thirty months after diagnosis, the patient developed urinary retention and right lower-limb paresis despite a normal WBC count, and an extradural tumor around the thoracic vertebrae and spinal cord compression were detected. The tumor was diagnosed as extranodal involvement of TCL1-family negative T-PLL, but the patient's general condition deteriorated rapidly, and no treatment was possible. T-PLL is a rare disease characterized by leukocytosis, and the WBC count generally increases with disease progression. Although blood counts are recommended for observation, it is important to keep in mind that the disease may worsen even if blood counts do not change.