Banz Yara, Krasniqi Fatime, Dirnhofer Stephan, Tzankov Alexander
Institute of Pathology, University Hospital Basel, Schönbeinstrasse 4, 4031, Basel, Switzerland.
BMC Clin Pathol. 2013 Jun 5;13:18. doi: 10.1186/1472-6890-13-18.
Angioimmunoblastic T-cell lymphoma is one of the most common types of peripheral T-cell lymphomas, usually presenting at an older age with an aggressive clinical course. Its characteristic morphological presentation and follicular helper T-cell phenotype help to distinguish it from other T-cell lymphomas.
We recently encountered the unique case of a 63-year old patient with relapsed tumour-cell rich angioimmunoblastic T-cell lymphoma, presenting with a "classical" phenotype and, in addition, an acquired, strong, aberrant expression of CD20."Lineage infidelity" of phenotypic markers is a well-documented phenomenon in lymphomas and leukemias, a circumstance currently still poorly understood and with the potential to bring about erroneous interpretations, causing diagnostic havoc. This case represents one of the few documented angioimmunoblastic T-cell lymphomas with strong CD20 expression. Of interest, CD20 expression was only detected in the recurrent lymphoma and not upon initial diagnosis. The clinical importance of this finding lies in the potential for treatment with an anti-CD20 antibody, for instance Rituximab, in addition to standard chemotherapy protocols for angioimmunoblastic T-cell lymphoma.
Diagnostic work-up of lymphomas to determine their lineage should therefore consider morphology, pheno- as well as genotypic characteristics, where appropriate, and in particular signs of progression and change in marker profile in relapsed cases e.g. acquisition of "non-lineage" markers such as CD20 in T-cell lymphoma.
血管免疫母细胞性T细胞淋巴瘤是外周T细胞淋巴瘤最常见的类型之一，通常在老年发病，临床病程侵袭性强。其特征性的形态学表现和滤泡辅助性T细胞表型有助于将其与其他T细胞淋巴瘤区分开来。
我们最近遇到了一例独特的病例，一名63岁复发性富含肿瘤细胞的血管免疫母细胞性T细胞淋巴瘤患者，表现出“经典”表型，此外，还获得性、强烈且异常表达CD20。表型标志物的“谱系不忠”是淋巴瘤和白血病中一个有充分记录的现象，目前对此情况仍了解甚少，有可能导致错误解读，造成诊断混乱。该病例是少数有记录的强CD20表达的血管免疫母细胞性T细胞淋巴瘤之一。有趣的是，CD20表达仅在复发性淋巴瘤中检测到，初诊时未检测到。这一发现的临床意义在于，除了血管免疫母细胞性T细胞淋巴瘤的标准化疗方案外，还可能使用抗CD20抗体（如利妥昔单抗）进行治疗。
因此，淋巴瘤的诊断检查以确定其谱系时，应酌情考虑形态学、表型以及基因型特征，特别是复发病例中的进展迹象和标志物谱的变化，例如T细胞淋巴瘤中获得“非谱系”标志物（如CD20）。
