Selumetinib as an Effective Therapy of Histiocytic Sarcoma Evolving From a B-Cell Acute Lymphoblastic Leukaemia.
Histiocytic sarcoma (HS) is a rare neoplasm derived from non-Langerhans histiocytic cells, exceptionally arising from B-ALL.
We present the case of a child with high-risk B-ALL with PAX5 P80R mutation.
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.
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.
The authors have confirmed clinical trial registration is not needed for this submission.
We present the case of a child with high-risk B-ALL with PAX5 P80R mutation.
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.
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.
The authors have confirmed clinical trial registration is not needed for this submission.
Authors
Largeaud Largeaud, Syrykh Syrykh, Vial Vial, Canali Canali, Luquet Luquet, Vergez Vergez, Dufrechou Dufrechou, Prade Prade, Baruchel Baruchel, Gerby Gerby, Nolla Nolla, Delabesse Delabesse, Pasquet Pasquet
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