中文摘要：

目的：探讨B细胞恶性肿瘤美罗华（rituximab）治疗后复发伴CD20抗原表达丢失患者的临床病理学特征、免疫学表型、治疗及预后。方法：回顾性分析1例滤泡型小裂细胞性淋巴瘤患者经美罗华治疗后转变为CD20阴性的弥漫大B细胞淋巴瘤的临床病理资料,并结合相关文献进行复习。结果：患者于1987年以左侧腮腺区淋巴结肿大为首发症状,1988年行左侧腮腺区淋巴结活检诊断为滤泡型小裂细胞性淋巴瘤,先后进行了50个疗程的＂COP、OP＂方案化疗及短期局部放疗。1998年出现白细胞升高及淋巴细胞百分数升高,骨髓穿刺诊断为慢性淋巴细胞白血病。2012年3月至2014年3月因白细胞急剧增高多次使用＂美罗华＂治疗,2014年3月患者出现咽喉部不适,行会厌部取检,诊断为右侧舌根部CD20阴性的弥漫大B细胞淋巴瘤,经过3个疗程的＂mini-CHOP＂治疗及2次＂美罗华＂治疗后右侧会厌部肿块消失,2015年5月再次出现右侧颈部淋巴结肿大,经活检诊断为CD20阳性的弥漫大B细胞淋巴瘤。结论：美罗华治疗恶性B细胞淋巴瘤后CD20抗原表达丢失在临床中并非罕见,建议临床中对于美罗华治疗复发或不敏感的病例重新取组织活检进行病理诊断、免疫标记,必要时进行分子遗传学检测,以免误诊,并可对复发病因的药物调整起到的积极指导作用。

英文摘要：

Objective： To investigate the clinicopathological features, immunological phenotype, treatment and prognosis of relapsed B-cell malignancies with loss of CD20 immunoreactivity after rituximab therapy. Methods： A retrospective analysis of one case of follicular small cleaved cell lymphoma which transformed to CD20-negative DLBCL after rituximab treatment was conducted. We reviewed and analyzed the clinicopathological features, immunological phenotype, treatment and prognosis of the patients. Results： We describe an 87-year-old male who initially presented with enlargement of left parotid lymph node in 1987. He was diagnosed with follicular small cleaved cell lymphoma through histological evaluation of left parotid lymph node biopsy in 1988. He was treated with 50 courses of cyclophosphamide, vincristine, prednisone（COP or OP）, and local irradiation therapy. In 1998, he developed a high white blood cell count and an increased percentage of lymphocytes. His bone marrow aspiration simultaneously showed chronic lymphocytic leukemia. He received some cycles of rituximab treatment due to a sharp increase in white blood cells from March 2012 to March 2014. He relapsed with a sore throat in March 2014, and the biopsy of right side of epiglottis revealed CD20-negative DLBCL. Then he received 2 cycles of rituximab combined with lowdose CHOP（mini-CHOP） before the mass in the right side of the epiglottis disappeared. While he relapsed again with the enlargement of right neck lymph node in May 2015, and the lymph node biopsy indicated CD20-positive DLBCL. Conclusion： It is not rare of the loss of CD20 antigen expression in malignant B-cell lymphoma after rituximab treatment. We recommend relapsed or non-sensitive patients after therapy with rituximab to rebiopsy for pathological diagnosis, immunohistochemistry, and even molecular genetic testing if necessary. These can reduce misdiagnosis, and play an important role in adjusting therapy of relapsed patients.