Flow cytometric features of incidental indolent T lymphoblastic proliferations

Fromm, Jonathan R.; Edlefsen, Kerstin L.; Cherian, Sindhu; Wood, Brent L.; Soma, Lori; Wu, David

doi:10.1002/cyto.b.21845

Cited by 13 publications

(21 citation statements)

References 14 publications

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“…Interestingly, Fromm et al . recently identified populations of T cells with varying stages of maturation in patients with iT‐LBP, suggesting that continuous release of immature T cells occurs from the thymus or extrathymic locations of T‐cell maturation 14 . Certainly, the absence of LMO2 expression in iT‐LBP is consistent with a thymic anatomical origin for iT‐LBPs, as TdT+ T cells in the thymus lack LMO2 expression 2,11 .…”

Section: Discussionmentioning

confidence: 87%

LIM domain only 2 (LMO2) expression distinguishes T‐lymphoblastic leukemia/lymphoma from indolent T‐lymphoblastic proliferations

et al. 2020

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LIM domain only 2 (LMO2) expression distinguishes T-lymphoblastic leukemia/lymphoma from indolent T-lymphoblastic proliferations Aims: 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. Methods and results: 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%). Conclusion: 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.

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Section: Discussionmentioning

confidence: 87%

LIM domain only 2 (LMO2) expression distinguishes T‐lymphoblastic leukemia/lymphoma from indolent T‐lymphoblastic proliferations

et al. 2020

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“…These findings are different from most IHC stain results reported, which were usually CD4+CD8+. TdT and cCD3 were almost always positive by either FCM anylysis or IHC stains, but the expression of sCD3, CD2, CD5, CD7, CD10, CD1a, and CD34 was variable [2,14]. CD33, a myeloid marker, is reportedly expressed in some iT-LBP cases [5,8].…”

Section: Discussionmentioning

confidence: 99%

“…BM studies showed the following karyotype (Fig. 3a): 47,XY,add(12)(p12),+21 [5]/ 49,sl,+8,+9 [1]/46,XY [14]/92,XXYY [5]. Fluorescence in situ hybridization (FISH) analysis showed loss of ETV6 (12p13) and gain of 21q22 (RUNX1) in 11.5%, and gain of 9q34 (ASS1, ABL1) in 4.5% of nuclei (Fig.…”

Section: Casementioning

confidence: 99%

T-lymphoblastic leukemia/lymphoma with interfollicular growth pattern and Castleman-like morphologic features

Kats

Cooley

et al. 2021

J Hematopathol

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Indolent T-lymphoblastic proliferation (iT-LBP) is a recently recognized benign pathologic condition commonly associated with Castleman disease. The lymph node of this condition shows preserved lymphoid architecture with proliferation of nonclonal Tlymphoblasts in the interfollicular area. iT-LBP is a rare condition and a diagnosis of exclusion. As a rule, it requires sophisticated techniques to exclude T-lymphoblastic leukemia/lymphoma (T-LBL/L). We present an unusual T-LBL/L in a lymph node mimicking iT-LBP. The case showed preserved nodal architecture, morphologic features of hyaline vascular Castleman disease, proliferation of T-lymphoblasts in the interfollicular area, and no clonal T-cell receptor gene rearrangement. The follow-up lymph node specimen excised 6 months later showed full-blown lymphoblastic lymphoma with an abnormal karyotype, near-early-Tprecursor phenotype, partial CD19 expression, and SETD2 mutation.

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“…Normal phenotypes may also be affected by microenvironmental factors, unrelated to treatment; Gadgeel and colleagues suggest in this issue (Gadgeel et al, 2021) that phenotypic maturation patterns in ectopic intrathyroidal thymic tissue differ from those described in normal thymus and thymoma (DiGiuseppe & Wood, 2019). Along these lines, microenvironmental cues have also been suggested to explain the apparent association between extrathymic immature T‐cell populations and Castleman disease (Fromm et al, 2020). One must also be alert for unexpected phenotypes in hematolymphoid neoplasms, such as the case of CD45‐negative follicular lymphoma reported by Khanlari and colleagues in the current issue (Khanlari et al, 2021).…”

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confidence: 99%

Issue Highlights—July 2021

DiGiuseppe¹

2021

Cytometry Part B Clinical

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Flow cytometric features of incidental indolent T lymphoblastic proliferations

Cited by 13 publications

References 14 publications

LIM domain only 2 (LMO2) expression distinguishes T‐lymphoblastic leukemia/lymphoma from indolent T‐lymphoblastic proliferations

LIM domain only 2 (LMO2) expression distinguishes T‐lymphoblastic leukemia/lymphoma from indolent T‐lymphoblastic proliferations

T-lymphoblastic leukemia/lymphoma with interfollicular growth pattern and Castleman-like morphologic features

Issue Highlights—July 2021

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