Department of Clinical Pathology, Robert-Bosch-Krankenhaus, Stuttgart, Germany.
Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart and University of Tuebingen, Tuebingen, Germany.
Histopathology. 2021 May;78(6):831-837. doi: 10.1111/his.14300. Epub 2020 Dec 25.
Plasmablastic lymphoma (PBL) is a rare aggressive B-cell lymphoma that frequently arises at extranodal sites in the setting of immunosuppression. The diagnosis of PBL is complex, owing to a frequent solid or cohesive growth pattern, and an often unusual immunophenotype. Several case reports have described cytokeratin (CK) expression in PBL, introducing a diagnostic pitfall. The aim of this study was to determine the frequency of CK expression in PBL in the largest series available to date.
By using immunohistochemistry in a cohort of 72 PBLs, we identified CK8/18 positivity in 11 of 72 cases (15%) and AE1/3 positivity in six of 65 cases (9%), clearly contrasting with a control series of non-PBL aggressive B-cell lymphomas (one of 96 diffuse large B-cell lymphomas), as well as with data in the literature describing only occasional CK expression in haematological neoplasms.
Our data indicate CK expression in a substantial number (15%) of PBLs. In view of the particular morphological features of PBL and its frequent negativity for the common leukocyte antigen and B-cell markers, this feature represents a pitfall in the routine diagnostic work-up of PBL, and requires more extensive immunohistochemical and molecular characterisation of cases entering the differential diagnosis.
浆母细胞淋巴瘤（PBL）是一种罕见的侵袭性 B 细胞淋巴瘤，常发生于免疫抑制状态下的结外部位。由于其常见的实性或黏附性生长模式以及非典型的免疫表型，PBL 的诊断较为复杂。已有数例报道描述了 PBL 中细胞角蛋白（CK）的表达，这引入了一个诊断陷阱。本研究旨在确定迄今为止最大系列中 PBL 中 CK 表达的频率。
通过对 72 例 PBL 进行免疫组织化学分析，我们发现 72 例中有 11 例（15%）呈 CK8/18 阳性，65 例中有 6 例（9%）呈 AE1/3 阳性，这与非 PBL 侵袭性 B 细胞淋巴瘤（96 例弥漫性大 B 细胞淋巴瘤中仅有 1 例）的对照组以及文献中仅描述少数血液肿瘤中 CK 偶尔表达的数据形成鲜明对比。
我们的数据表明 CK 在相当数量（15%）的 PBL 中表达。鉴于 PBL 的特殊形态学特征及其对常见白细胞抗原和 B 细胞标志物的频繁阴性，这一特征代表了 PBL 常规诊断工作中的一个陷阱，需要对进入鉴别诊断的病例进行更广泛的免疫组织化学和分子特征分析。
