Pediatric T-cell lymphoblastic lymphoma with t(9;17)(q34;q23)-associated N-terminally truncated NOTCH1 activation: a case report.

T-cell lymphoblastic lymphoma (T-LBL) is an aggressive malignancy that comprises 20% of pediatric non-Hodgkin lymphoma cases. Most T-LBLs harbor NOTCH1 point mutations or small indels, which are generally associated with favorable outcomes. In contrast, the clinical impact of structural rearrangements involving NOTCH1 remains poorly understood. We describe the case of a 6-year-old boy with T-LBL carrying a MIR142HG::NOTCH1 fusion from a t(9;17)(q34;q23) translocation, resulting in a truncated, constitutively active NOTCH1 protein. The patient experienced an aggressive course and died shortly after cord blood transplantation. Literature review suggests that 9q34 translocations in T-LBL portend poor prognosis, highlighting truncated NOTCH1 as a potential therapeutic target.