Detection of L265P MYD‐88 mutation in a series of clonal B‐cell lymphocytosis of marginal zone origin (CBL‐MZ) |
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| Authors: | Christina Kalpadakis Gerassimos A. Pangalis Theodoros P. Vassilakopoulos Maria Roumelioti Sotirios Sachanas Penelope Korkolopoulou Efstathios Koulieris Maria Moschogiannis Xanthi Yiakoumis Pantelis Tsirkinidis Charalampos Pontikoglou Dimitra Rondoyianni Helen A. Papadaki Panayiotidis Panayiotidis Maria K. Angelopoulou |
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| Affiliation: | 1. Department of Haematology, University of Crete, Heraklion, Crete, Greece;2. Department of Haematology, Athens Medical Center Psychikon Branch, Athens, Greece;3. Department of Haematology, Laikon General Hospital, University of Athens, Athens, Greece;4. 1st Department of Propedeutics, Laikon General Hospital, University of Athens, Athens, Greece;5. 1st Department of Anatomic Pathology, University of Athens, Athens, Greece;6. Department of Anatomic Pathology, Evangelismos Hospital of Athens, Athens, Greece |
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| Abstract: | Clonal B‐cell lymphocytosis of marginal zone origin (CBL‐MZ) is a recently described entity characterized by the presence of clonal B cells in the blood and/or bone marrow (BM) with morphologic and immunophenotypic features consistent with marginal zone derivation in otherwise healthy individuals. CBL‐MZ is commonly associated with paraproteinemia, usually immunoglobulin M (IgM), raising diagnostic difficulties from Waldenstrom macroglobulinemia (WM). The aim of the present study was to determine the presence of MYD‐88 L265P mutation in a well‐characterized series of CBL‐MZ to identify cases that may in fact represent WM. Fifty‐three CBL‐MZ cases were retrospectively evaluated. MYD‐88 L265P mutation was determined by allele‐specific polymerase chain reaction in blood and/or BM mononuclear cells. Almost half of the CBL‐MZ cases (49%) were associated with paraproteinemia mainly of the IgM type (65%). MYD‐88 L265P mutation was identified in 10 cases (19%). These cases may truly represent WM, whereas 43 cases (81%) are still classified as CBL‐MZ. Mutated cases were all associated with paraproteinemia compared with 37% of the nonmutated ones (P < .0001). In addition, mutated cases displayed more frequently CD38 and CD25 positivity (P = .002 and P = .005, respectively). Moreover, cases without paraproteinemia presented more frequently with lymphocytosis, irrespective of the presence of the MYD‐88 mutation (P = .02). The present study demonstrates that MYD‐88 L265P mutation may represent the only sensitive marker for the differentiation of CBL‐MZ from probable WM. However, further studies are warranted to better define the biological significance of MYD‐88 L265P mutation and to clarify whether the presence of the mutation establishes WM diagnosis or that it can also be present in borderline cases associated with paraproteinemia. |
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| Keywords: | clonal B‐cell lymphocytosis MYD‐88 L265P mutation |
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