摘要目的:探讨血管内大B细胞淋巴瘤（IVLBCL）的临床病理学特点及MYD88 L265P基因突变情况。方法:收集郑州大学第一附属医院2014年3月至2019年12月诊断的IVLBCL 14例，分析其临床病理学特点及预后，原位杂交法检测EB病毒，Sanger测序法检测MYD88 L265P基因突变情况。结果:患者男性6例，女性8例，中位年龄62岁（年龄范围48~73岁）；PET-CT示累及：肾上腺7例，骨6例，中枢神经4例，皮肤、女性生殖系统及病灶局域淋巴结各3例，前列腺、肝及脾各2例，蝶窦、阴茎、膀胱及右肺各1例；临床症状以发热最多见（7例），神经症状及下腹痛各2例，皮疹伴水肿、双下肢无力伴麻木及停经后阴道出血伴排便困难各1例；患者多处于Lugano Ⅳ期（11例）；伴噬血细胞综合征（HPS）4例；累及骨髓6例。镜下：瘤细胞主要聚集于小~中等大血管或血窦内；肿瘤细胞体积偏大，核圆形或卵圆形、略不规则，染色质粗糙，核仁明显1~3个，1例可见胚胎样核；2例局部见血管外弥漫大B细胞淋巴瘤成分。免疫表型：14例肿瘤细胞CD20、CD79α均弥漫强阳性，12例均为非生发中心细胞表型（non-GCB），6/11为双表达淋巴瘤，7/12 CD5阳性；12/12 EBER均阴性；1/10 MYD88 L265P突变。随访时间0.5~24.0个月，11例存活，3例死亡。结论:IVLBCL罕见，国内患者临床表现以亚洲型多见，肿瘤细胞少，结合临床特点及免疫组织化学可减少漏诊及误诊；IVLBCL可伴有MYD88 L265P突变，其突变率仍需进一步研究。

abstractsObjective:To study the clinicopathologic features and MYD88 L265P mutation status of intravascular large B cell lymphoma (IVLBCL).Methods:Fourteen cases of IVLBCLs were diagnosed from March 2014 to December 2019 at the First Affiliated Hospital of Zhengzhou University. The clinicopathologic features and prognosis were analyzed. Epstein-Barr virus encoded RNAs and MYD88 L265P mutation status were detected using in situ hybridization and Sanger sequencing, respectively. The follow-up data were obtained by telephone interview.Results:There were 6 males and 8 females with a median age of 62 years (range: 48-73 years). The involved anatomic locations were demonstrated by positron emission tomography-computed tomography, including adrenal gland (7/14), bone (6/14), central nerve system (4/14), skin (3/14), female reproductive system (3/14), local lymph nodes (3/14), prostate (2/14), liver and spleen (2/14), sphenoid sinus (1/14), penis (1/14), bladder (1/14), and right lung (1/14). Fever was the most common symptom (7/14), followed by neurologic symptoms and lower abdominal pain (2/14 each). The reminder symptoms included rash with edema, legs weakness and numbness, or postmenopausal bleeding (1/14 each). Eleven cases were at Lugano stage Ⅳ. Four cases were associated with the hemophagocytic syndrome, while 6 cases with bone marrow involved. Microscopically, the tumor cells were generally concentrated within the small-to-medium vascular lumens or sinusoids; they had centroblast-like appearance and showed large round or oval nuclei with slightly irregularities, coarse chromatin and 1-3 distinct nucleoli. One exception was the one case with an embryoid nuclei, reminiscent of anaplastic large cell lymphoma. The mitosis was not uncommon. Extravascular neoplastic cells were seen in two cases. The neutrophils could be appreciable in most of the cases (10/14). Immunophenotyping showed that CD20 and CD79α were diffusely and strongly positive in 14 cases; 12 cases were classified as the non-GCB subtype; 6 out of the 11 cases were double expressor lymphoma; 7 out of the 12 cases were CD5-positive. Twelve cases were EBER negative. The MYD88 L265P mutation was detected in 1 case (1/10). The duration of the follow-up ranged from 0.5 to 24.0 months, and 11 patients survived and 3 died.Conclusions:IVLBCL is rare. The most common type of IVLBCL in China is Asian type with scant tumor cells. Combination of clinical and immunohistochemical features can avoid most, if not all, misdiagnoses and missed diagnoses. Some IVLBCL cases may harbor the MYD88 L265P mutation, but the prevalence of MYD88 L265P mutation in the population still warrants additional studies.