Wen Kwun Wah, Gill Ryan M
Department of Pathology, University of California, San Francisco.
Liver Center, University of California, San Francisco, San Francisco, CA.
Appl Immunohistochem Mol Morphol. 2019 Apr;27(4):319-324. doi: 10.1097/PAI.0000000000000596.
Terminal deoxynucleotidyl transferase (TdT) is a nuclear enzyme restricted to precursor lymphoid cells and their malignant counterparts; immunohistochemical TdT labeling is helpful in recognition of lymphoblasts, which can resemble mature lymphocytes. The diagnosis of B-lymphoblastic leukemia/lymphoma (B-ALL) is occasionally first encountered on liver core biopsy, but TdT immunostain specificity for B-ALL is not clearly established in this setting, which can be problematic when only a few TdT-positive cells are identified. In this study, we evaluated the incidence and distribution of immature B lymphocytes coexpressing TdT and PAX-5, in pediatric and adult liver biopsies, to determine whether a normal complement of hepatic immature B cells can be detected, which must be recognized in a workup to exclude B-ALL. We selected 41 pediatric and adult liver biopsies with a significant portal and/or sinusoidal hematolymphoid infiltrate and performed immunohistochemical stains for TdT and PAX-5 to identify and categorize distribution of immature B cells. TdT-positive cells were detected in 40% of pediatric liver biopsies with a significant hematolymphoid infiltrate (4/10), which included all biopsies from neonates (and infants under 9 wk of age). In adults, immature B-cell infiltrates were less common (6%, 2/31). Dual immunostaining was performed on 2 cases of neonatal hepatitis, which documented B-cell lineage in at least a subset of TdT-positive cells and there was no colabeling with CD3. Immature B cells can be detected in liver biopsies in a variety of clinical settings, most commonly in children, and presence of a few TdT-positive cells cannot be considered entirely specific for involvement by B-ALL. Further workup for B-ALL can be warranted if there is more extensive multifocal portal and/or sinusoidal involvement by blasts with TdT labeling.
末端脱氧核苷酸转移酶（TdT）是一种仅限于前体淋巴细胞及其恶性对应细胞的核酶；免疫组化TdT标记有助于识别可能类似于成熟淋巴细胞的淋巴母细胞。B淋巴细胞白血病/淋巴瘤（B-ALL）的诊断偶尔首先在肝脏穿刺活检中遇到，但在这种情况下，TdT免疫染色对B-ALL的特异性尚未明确确立，当仅识别出少数TdT阳性细胞时可能会出现问题。在本研究中，我们评估了儿科和成人肝脏活检中同时表达TdT和PAX-5的未成熟B淋巴细胞的发生率和分布，以确定是否能检测到正常数量的肝脏未成熟B细胞，这在排除B-ALL的检查中必须予以识别。我们选择了41例具有显著门静脉和/或窦状隙血液淋巴细胞浸润的儿科和成人肝脏活检标本，并对TdT和PAX-5进行免疫组化染色，以识别和分类未成熟B细胞的分布。在40%具有显著血液淋巴细胞浸润的儿科肝脏活检标本（4/10）中检测到TdT阳性细胞，其中包括所有新生儿（以及9周龄以下婴儿）的活检标本。在成人中，未成熟B细胞浸润较少见（6%，2/31）。对2例新生儿肝炎病例进行了双重免疫染色，结果表明至少一部分TdT阳性细胞为B细胞系，且未与CD3共标记。在各种临床情况下，肝脏活检中均可检测到未成熟B细胞，最常见于儿童，少数TdT阳性细胞的存在不能完全视为B-ALL累及的特异性表现。如果有更广泛的多灶性门静脉和/或窦状隙被TdT标记的母细胞累及，则有必要进一步检查是否为B-ALL。
