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LIM domain only 2 (LMO2) expression distinguishes T‐lymphoblastic leukemia/lymphoma from indolent T‐lymphoblastic proliferations
Author(s) -
Brar Nivaz,
Butzmann Alexandra,
Kumar Jyoti,
Peerani Raheem,
Morgan Elizabeth A,
Grigoriadis George,
Kumar Beena,
Tatarczuch R Maciej,
Warnke Roger A,
Ohgami Robert S
Publication year - 2020
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.14176
Subject(s) - immunohistochemistry , lymphoma , lymphoblastic lymphoma , terminal deoxynucleotidyl transferase , pathology , medicine , lymphoblastic leukemia , leukemia , biology , t cell , immunology , tunel assay , immune system
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.