California Northstate University, Elk Grove, CA, USA.
Department of Pathology, University of California San Francisco, San Francisco, CA, USA.
Histopathology. 2020 Dec;77(6):984-988. doi: 10.1111/his.14176. Epub 2020 Sep 24.
An indolent T-lymphoblastic proliferation (iT-LBP) is a benign, reactive expansion of immature terminal deoxynucleotidyl transferase (TdT)-positive T cells found in extrathymic tissues. iT-LBP can be challenging to distinguish from malignant processes, specifically T-lymphoblastic lymphoma (T-LBL), given the overlapping clinical and histological features. Recently, it has been shown that LIM domain only 2 (LMO2) is overexpressed in T-LBL but not in reactive immature TdT+ T cells in the thymus. On the basis of these findings, the aim of this study was to investigate the expression of LMO2 by using immunohistochemistry and its role in differentiating iT-LBPs from T-LBLs.
We retrospectively identified cases of iT-LBP and T-LBL from the pathology archives of four institutions. Seven iT-LBP cases (including five new cases that have not been reported in the literature) and 13 T-LBL cases were analysed. Clinical, morphological, immunophenotypic and molecular data were analysed. Immunohistochemical staining with LMO2 was performed on all iT-LBP and T-LBL cases. A review of five new iT-LBP cases showed similar morphological, immunophenotypic and molecular features to those of previously reported cases. All iT-LBP cases were negative for LMO2 (0/7), whereas 92% of T-LBL cases (12/13) expressed LMO2; the sensitivity was 92% (confidence interval 64-100%) and the specificity was 100% (confidence interval 59-100%).
We confirm previously published findings that iT-LBP cases show highly overlapping morphological and immunophenotypic features with T-LBL. Importantly, LMO2 expression is a sensitive and specific marker with which to rule out iT-LBP.
惰性 T 淋巴母细胞增生症（iT-LBP）是一种良性、反应性的不成熟末端脱氧核苷酸转移酶（TdT）阳性 T 细胞在胸腺外组织中的扩张。由于重叠的临床和组织学特征，iT-LBP 很难与恶性过程，特别是 T 淋巴母细胞淋巴瘤（T-LBL）区分开来。最近，已经表明 LIM 结构域只有 2（LMO2）在 T-LBL 中过度表达，但在胸腺中的反应性不成熟 TdT+T 细胞中不表达。基于这些发现，本研究旨在通过免疫组织化学检测 LMO2 的表达，并探讨其在鉴别 iT-LBP 和 T-LBL 中的作用。
我们从四个机构的病理档案中回顾性地确定了 iT-LBP 和 T-LBL 病例。分析了 7 例 iT-LBP 病例（包括 5 例未在文献中报道的新病例）和 13 例 T-LBL 病例。分析了临床、形态学、免疫表型和分子数据。对所有 iT-LBP 和 T-LBL 病例进行了 LMO2 免疫组织化学染色。对 5 例新的 iT-LBP 病例的回顾显示，其形态学、免疫表型和分子特征与之前报道的病例相似。所有 iT-LBP 病例均为 LMO2 阴性（0/7），而 92%的 T-LBL 病例（12/13）表达 LMO2；敏感性为 92%（置信区间 64-100%），特异性为 100%（置信区间 59-100%）。
我们证实了之前发表的发现，即 iT-LBP 病例与 T-LBL 具有高度重叠的形态学和免疫表型特征。重要的是，LMO2 表达是一种敏感和特异的标志物，可以排除 iT-LBP。
