Department of Pathology and Laboratory Medicine, Istituto Nazionale Tumori, 20133 Milano, Italy.
Hum Pathol. 2010 May;41(5):621-31. doi: 10.1016/j.humpath.2009.10.027.
Published in September 2008, the updated World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues introduces provisional borderline categories for lymphoma cases that demonstrate overlapping clinical, morphological, and/or immunophenotypic features between well-established entities. These overlapping features pose real diagnostic challenges especially in identifying atypical cases of diffuse large B-cell lymphoma, Hodgkin lymphoma, and Burkitt lymphoma. Lymphoma cases showing borderline features between T-cell/histiocyte-rich large B-cell lymphoma and nodular lymphocyte predominant Hodgkin lymphoma are not included within the borderline categories provisionally recognized by the updated classification. Within the borderline categories, there are cases combining features of primary mediastinal large B-cell lymphoma and classical Hodgkin lymphoma. Many of these cases resemble classical Hodgkin lymphoma but have a large number of tumor cells expressing CD20, CD45, and B-cell transcription factors. Alternatively, these cases may resemble primary mediastinal large B-cell lymphoma but contain tumor cells resembling Reed-Sternberg cells and displaying an aberrant phenotype such as CD20(-), CD15(-/+) CD45(+), CD30(+), Pax5(+), OCT2(+/-), and BOB1(+/-). Another new borderline category defining B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma, represents a biologically heterogeneous group. Cases with morphologic features intermediate and with CD10/BCL6 coexpression should be placed in diffuse large B-cell lymphoma/Burkitt lymphoma category if tumor cells also show strong BCL2 staining and/or a Ki67 proliferation index of less than 90%. When MYC rearrangements are present in these cases, the lymphomas often have atypical features, including concurrent rearrangements of BCL2 and/or BCL6 genes (so-called double/triple-hit lymphomas) and more aggressive behavior. For the provisional borderline categories, unresolved issues include understanding molecular pathogenesis and defining an effective treatment.
2008 年 9 月发布的《世界卫生组织造血和淋巴组织肿瘤分类》更新版为那些在形态学、临床和/或免疫表型上介于两种明确实体之间的淋巴瘤病例引入了暂定的交界类别。这些重叠特征给诊断带来了真正的挑战，尤其是在识别弥漫性大 B 细胞淋巴瘤、霍奇金淋巴瘤和伯基特淋巴瘤的非典型病例时。在更新分类中，暂定的交界类别中不包括 T 细胞/组织细胞丰富的大 B 细胞淋巴瘤和结节性淋巴细胞为主型霍奇金淋巴瘤之间具有交界特征的淋巴瘤病例。在交界类别中，有一些病例结合了原发性纵隔大 B 细胞淋巴瘤和经典霍奇金淋巴瘤的特征。这些病例中的许多与经典霍奇金淋巴瘤相似，但有大量表达 CD20、CD45 和 B 细胞转录因子的肿瘤细胞。或者，这些病例可能与原发性纵隔大 B 细胞淋巴瘤相似，但含有类似于 Reed-Sternberg 细胞的肿瘤细胞，并表现出异常表型，如 CD20(-)、CD15(-/+) CD45(+)、CD30(+)、Pax5(+/-)、OCT2(+/-)和 BOB1(+/-)。另一个新的交界类别定义为具有弥漫性大 B 细胞淋巴瘤和伯基特淋巴瘤之间特征的不可分类的 B 细胞淋巴瘤，代表了一组具有生物学异质性的肿瘤。如果肿瘤细胞也表现出强烈的 BCL2 染色和/或 Ki67 增殖指数小于 90%，则具有形态学特征介于弥漫性大 B 细胞淋巴瘤和伯基特淋巴瘤之间的病例应归入弥漫性大 B 细胞淋巴瘤/伯基特淋巴瘤类别。当这些病例中存在 MYC 重排时，淋巴瘤通常具有非典型特征，包括 BCL2 和/或 BCL6 基因的同时重排（所谓的双/三打击淋巴瘤）和更具侵袭性的行为。对于暂定的交界类别，尚未解决的问题包括理解分子发病机制和定义有效的治疗方法。
