Acute leukaemia with ZNF384-TCF3 fusion is considered high risk in contemporary frontline treatment protocols and will be treated by Hematopoietic Stem Cell Transplantation (HSCT) or Chimeric Antigen Receptor T-cell (CART) treatment in first complete remission. Although current cytogenetic and molecular work-up of newly diagnosed paediatric acute lymphoblastic leukaemia (ALL) includes the identification of the TCF3-ZNF384 fusion, this case underscores the importance of including this information in the choice of bridging therapy and the timing of CART treatment, as the high cytokine levels during high grade Cytokine Release Syndrome (CRS) might drive ALL cells to lineage switching.

(BELG J HEMATOL 2022;13(3):128–32)