Selumetinib as an Effective Therapy of Histiocytic Sarcoma Evolving From a B-Cell Acute Lymphoblastic Leukaemia.
[INTRODUCTION] Histiocytic sarcoma (HS) is a rare neoplasm derived from non-Langerhans histiocytic cells, exceptionally arising from B-ALL.
APA
Largeaud L, Syrykh C, et al. (2026). Selumetinib as an Effective Therapy of Histiocytic Sarcoma Evolving From a B-Cell Acute Lymphoblastic Leukaemia.. EJHaem, 7(2), e70216. https://doi.org/10.1002/jha2.70216
MLA
Largeaud L, et al.. "Selumetinib as an Effective Therapy of Histiocytic Sarcoma Evolving From a B-Cell Acute Lymphoblastic Leukaemia.." EJHaem, vol. 7, no. 2, 2026, pp. e70216.
PMID
41798885
Abstract
[INTRODUCTION] Histiocytic sarcoma (HS) is a rare neoplasm derived from non-Langerhans histiocytic cells, exceptionally arising from B-ALL.
[METHODS] We present the case of a child with high-risk B-ALL with PAX5 P80R mutation.
[RESULTS] Despite initial remission, a chemoresistant paravertebral mass was identified as HS. A shared IGK/TCRB rearrangements and PAX5 alterations between the leukaemic and histiocytic clones suggested transdifferentiation driven by PAX5. A somatic MAP2K1 mutation in the HS component prompted selumetinib treatment, leading to a rapid response.
[CONCLUSION] This case underscores the role of PAX5 in lineage plasticity and highlights the potential of targeted MEK inhibition in MAPK-driven HS arising from B-ALL.
[TRIAL REGISTRATION] The authors have confirmed clinical trial registration is not needed for this submission.
[METHODS] We present the case of a child with high-risk B-ALL with PAX5 P80R mutation.
[RESULTS] Despite initial remission, a chemoresistant paravertebral mass was identified as HS. A shared IGK/TCRB rearrangements and PAX5 alterations between the leukaemic and histiocytic clones suggested transdifferentiation driven by PAX5. A somatic MAP2K1 mutation in the HS component prompted selumetinib treatment, leading to a rapid response.
[CONCLUSION] This case underscores the role of PAX5 in lineage plasticity and highlights the potential of targeted MEK inhibition in MAPK-driven HS arising from B-ALL.
[TRIAL REGISTRATION] The authors have confirmed clinical trial registration is not needed for this submission.