Nivaz Brar1, Alexandra Butzmann2, Jyoti Kumar3, Raheem Peerani3, Elizabeth A Morgan4, George Grigoriadis5, Beena Kumar5, R Maciej Tatarczuch5, Roger A Warnke3, Robert S Ohgami2. 1. California Northstate University, Elk Grove, CA, 95757, USA. 2. Department of Pathology, University of California San Francisco, San Francisco, CA, 94143, USA. 3. Department of Pathology, Stanford University, Stanford, CA, 94305, USA. 4. Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA. 5. Department of Pathology, Monash Health, Melbourne, VIC, 3004, Australia.
Abstract
AIMS: An indolent T-lymphoblastic proliferation (iT-LBP) is a benign, reactive expansion of immature TdT+ 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 histologic 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. Based on these findings, we investigated the expression of LMO2 by immunohistochemistry and its role in differentiating iT-LBPs from T-LBLs. METHODS: We retrospectively identified cases of iT-LBP and T-LBL from the pathology archives of four institutions. Seven cases of iT-LBP (including five new cases that have not been reported in the literature) and 13 cases of T-LBL were analyzed. Clinical, morphologic, immunophenotypic and molecular data were analyzed. Immunohistochemical staining with LMO2 was performed on all cases of iT-LBP and T-LBL. RESULTS: A review of five new cases of iT-LBP showed similar morphologic, immunophenotypic and molecular features to prior reported cases. All cases of iT-LBP were negative for LMO2 (0/7) while 92% of T-LBL cases (12/13) expressed LMO2; sensitivity 92% (confidence interval 64-100%) and specificity 100% (confidence interval 59-100%). CONCLUSION: We confirm prior published findings that cases of iT-LBPs demonstrate highly overlapping morphologic and immunophenotypic features when compared to T-LBL. Importantly, expression of LMO2 is a sensitive and specific marker to rule out iT-LBP. This article is protected by copyright. All rights reserved.
AIMS: An indolent T-lymphoblastic proliferation (iT-LBP) is a benign, reactive expansion of immature TdT+ 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 histologic 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. Based on these findings, we investigated the expression of LMO2 by immunohistochemistry and its role in differentiating iT-LBPs from T-LBLs. METHODS: We retrospectively identified cases of iT-LBP and T-LBL from the pathology archives of four institutions. Seven cases of iT-LBP (including five new cases that have not been reported in the literature) and 13 cases of T-LBL were analyzed. Clinical, morphologic, immunophenotypic and molecular data were analyzed. Immunohistochemical staining with LMO2 was performed on all cases of iT-LBP and T-LBL. RESULTS: A review of five new cases of iT-LBP showed similar morphologic, immunophenotypic and molecular features to prior reported cases. All cases of iT-LBP were negative for LMO2 (0/7) while 92% of T-LBL cases (12/13) expressed LMO2; sensitivity 92% (confidence interval 64-100%) and specificity 100% (confidence interval 59-100%). CONCLUSION: We confirm prior published findings that cases of iT-LBPs demonstrate highly overlapping morphologic and immunophenotypic features when compared to T-LBL. Importantly, expression of LMO2 is a sensitive and specific marker to rule out iT-LBP. This article is protected by copyright. All rights reserved.