Department of Pathology, City of Hope Medical Center, Duarte, CA, USA.
Am J Surg Pathol. 2012 Aug;36(8):1129-40. doi: 10.1097/PAS.0b013e31825b38ec.
Primary effusion lymphoma (PEL) is a rare form of aggressive B-cell lymphoma in HIV patients, which typically presents with lymphomatous effusions in the body cavities without forming mass lesions. PEL is associated with Kaposi sarcoma-associated herpesvirus (KSHV) (also called human herpesvirus-8) with distinct clinical and pathologic features. Rare cases of KSHV-associated large B-cell lymphoma (KSHV-LBL) have been observed in the lymph nodes or extranodal sites without lymphomatous effusions during the course of disease. KSHV-LBL is generally similar to classic PEL on the basis of the clinical presentation (HIV(+) male), morphology (immunoblastic, plasmablastic, or anaplastic), immunophenotype (CD45(+), CD20(-), CD79a(-), CD30(+), CD138(+), and EMA(+)), presence of Epstein-Barr virus infection, and clonal immunoglobulin gene rearrangements. However, it is not clear whether KSHV-LBL is a distinct entity or represents part of the spectrum of classic PEL; in particular, there is no consensus diagnostic term for KSHV-LBL. In this study, we investigated the clinicopathologic features of 9 cases of KSHV-LBL from our files. An additional 43 such cases and 84 cases of classic PEL from the English literature were reviewed and compared with each other. In contrast to the classic PEL, KSHV-LBL had a very significant lower expression of CD45 (74% vs. 94%, P=0.004) but significant higher expression of CD20 (17% vs. 5%, P=0.04) and CD138 (70% vs. 38%, P=0.05). KSHV-LBL also had slightly higher positivity of CD79a (23% vs. 5%, P=0.13) and immunoglobulin light chain expression, although the difference was not statistically significant [κ chain (12% vs. 0%) and λ chain (31% vs. 21%)]. The expressions of EMA and CD30 were slightly lower in KSHV-LBL compared with those observed in PEL (57% vs. 75% and 63% vs. 76%, respectively). Interestingly, 29% (10/34) of cases of KSHV-LBL revealed aberrant CD3 expression, which may mislead to a diagnosis of T-cell lymphoma, particularly anaplastic large cell lymphoma in combination with the anaplastic morphology and expression of CD30 and EMA. Although KSHV-LBL shows different clinical presentations and some variations in immunophenotype from classic PEL, it is still uncertain, on the basis of our findings, whether it is justifiable to separate them as 2 distinct entities. Nevertheless, we feel it is necessary to have a consensus diagnostic term, and we recommend a tentative one as "KSHV-associated large B-cell lymphoma (KSHV-LBL)" to replace many different names previously used.
原发性渗出性淋巴瘤（PEL）是一种罕见的侵袭性 B 细胞淋巴瘤，发生于 HIV 感染者，通常表现为体腔的淋巴瘤性渗出，而无肿块形成。PEL 与卡波西肉瘤相关疱疹病毒（KSHV）（也称为人类疱疹病毒 8）相关，具有独特的临床和病理特征。在疾病过程中，偶尔会观察到 KSHV 相关的大 B 细胞淋巴瘤（KSHV-LBL）在淋巴结或结外部位出现，而无淋巴瘤性渗出。KSHV-LBL 在临床表现（HIV(+)男性）、形态学（免疫母细胞型、浆母细胞型或间变性）、免疫表型（CD45(+)、CD20(-)、CD79a(-)、CD30(+)、CD138(+)和 EMA(+)）、存在 EBV 感染和克隆性免疫球蛋白基因重排方面与经典 PEL 基本相似。然而，目前尚不清楚 KSHV-LBL 是否为一种独特的实体，或者是否代表经典 PEL 谱的一部分；特别是，尚无用于 KSHV-LBL 的共识诊断术语。在这项研究中，我们调查了我们档案中 9 例 KSHV-LBL 的临床病理特征。还回顾并比较了来自英文文献的另外 43 例此类病例和 84 例经典 PEL。与经典 PEL 相比，KSHV-LBL 的 CD45 表达显著降低（74%对 94%，P=0.004），但 CD20 和 CD138 的表达显著升高（17%对 5%，P=0.04；70%对 38%，P=0.05）。KSHV-LBL 的 CD79a 表达也略高（23%对 5%，P=0.13），免疫球蛋白轻链表达略高，尽管差异无统计学意义[κ 链（12%对 0%）和 λ 链（31%对 21%）]。与 PEL 相比，KSHV-LBL 中 EMA 和 CD30 的表达略低（分别为 57%对 75%和 63%对 76%）。有趣的是，34 例 KSHV-LBL 中有 29%（10/34）显示异常的 CD3 表达，这可能导致误诊为 T 细胞淋巴瘤，尤其是间变性大细胞淋巴瘤，结合间变性形态和 CD30 和 EMA 的表达。尽管 KSHV-LBL 与经典 PEL 相比具有不同的临床表现和免疫表型的一些变化，但根据我们的发现，是否可以将其分为 2 个不同的实体尚不确定。然而，我们认为有必要有一个共识的诊断术语，我们建议使用一个暂定的术语，即“KSHV 相关的大 B 细胞淋巴瘤（KSHV-LBL）”来替代以前使用的许多不同的名称。
