胸腺原发性黏膜相关淋巴组织淋巴瘤2例及文献复习

  目的  探讨胸腺原发性黏膜相关淋巴组织淋巴瘤的临床病理特征、免疫组化和基因重排特点。  方法  复习2例胸腺原发性黏膜相关淋巴组织淋巴瘤的临床资料, 通过光镜观察、免疫组化染色(EnVision, 抗体包括CD3, CD20, CD79α, CD5, Bcl-2, Bcl-6, CD10, CD23, CyclinD1, AE1/AE3)、聚合酶链式反应(polymerase chain reaction, PCR)分析其临床病理特征、免疫组化和基因重排特点。  结果  2例患者均为汉族, 男女各1例, 年龄分别为57岁和53岁, 女性患者伴干燥综合征(Sj?gren's syndrome, SS)及过敏性紫癜。术前CT、磁共振成像(magnetic resonance imaging, MRI)及术后大体检查均可见边界清楚的肿物, 内含小囊。镜下可见成片的小到中等大小弥漫淋巴细胞, 主要是中心细胞样细胞和/或单核样淋巴细胞, 偶见中心母细胞或免疫母细胞样细胞。小血管丰富, 血管周围可见较多浆细胞; 并可见多房囊肿, 囊壁被覆鳞状上皮细胞及柱状上皮细胞, 伴淋巴上皮病变, 囊壁Hassall小体增多并囊性退变, 内见粉染物; 存在反应性增生的淋巴滤泡, 周围脂肪组织内散见多处小结节。免疫组化显示CD20、CD79α和Bcl-2弥漫阳性, 囊肿上皮及赫氏小体(Hassall's corpuscle)AE1/AE3阳性, 上皮间可见CD20阳性的淋巴细胞浸润。PCR显示2例免疫球蛋白重链可变区(immunoglobulin heavy chain variable region, IgHV)基因重排阳性。2例患者均开胸行肿物及部分胸腺切除术, 术后分别随访27和6个月, 未见复发及转移。  结论  胸腺黏膜相关淋巴组织淋巴瘤少见, 具有明显特点:亚洲人多发, 伴有自身免疫性疾病, 大体及镜下可见多房囊肿, 血管周围可见明显的浆细胞分化, 缺乏凋亡抑制蛋白2-黏膜相关淋巴瘤转位基因1(API2-MALT1)融合基因等。手术切除为首选治疗, 临床结局良好。

Mucosa-associated Lymphoid Tissue Lymphoma of the Thymus:A Stuty of 2 Cases

Objective To study the clinicopathologic features and diagnosis of mucosa-associated lymphoid tissue(MALT) lymphoma of the thymus.Methods The clinical,pathologic,immunohistochemical and polymerase chain reaction(PCR) findings of two patients(one 57-year-old Chinese Han man and one 53-year-old Chinese Han woman) with thymic MALT lymphoma were retrospectively analyzed.Results Pre-operative computed tomography(CT) and magnetic resonance imaging(MRI) images and gross examination showed well-demarcated masses with multilocular cysts.Microscopy showed that the centrocyte-like lymphocytes formed broad,pale-staining bands and sheets,with frequent presence of epithelium-lined cysts and consistent plasma cell differentiation around small vessels.The dilated Hassall’s corpuscle with eosinophilic material was observed.The lymphoepithelial lesions and reactive lymphoid follicle hyperplasia were common.Many small nodules,full of the lymphoma cells,located in the adipose tissue.The tumor cells were immunoreactive for CD20,CD79α,and Bcl-2.Immunostaining for AE1/AE3 highlighted the Hassall’s corpuscles and epithelium lining the cysts.PCR for immunoglobulin heavy chain variable region(IgHV) rearrangements showed distinct bands indicating monoclonality in both two cases.No recurrence or metastasis was noted 27 and 6 months after surgery.Conclusions Thymus MALT lymphoma is rare,and may represent a distinct subgroup of MALT lymphoma characterized by apparent predilection for Asians.It has a strong association with autoimmune disease,frequent presence of cysts,consistent plasma cell differentiation,and consistent lack of API2-MALT1 gene fusion.Surgery is the treatment of choice,usually resulting in good outcome.