Primary CNS Anaplastic Large Cell Lymphoma DUPS22 Rearranged with Gain of ALK: A Case Report and Review of the Literature.

ALK-negative anaplastic large cell lymphoma (ALCL) is a rare primary central nervous system lymphoma (PCNSL). Although DUSP22 rearrangement is considered favorable in systemic ALK-negative ALCL, survival remains poor in PCNSL. We report a case of PCNSL ALK-negative ALCL with DUSP22-IRF4 rearrangement and an unusual gain of the ALK gene (2p23), complicated by transaminitis, treated with high-dose methotrexate followed by whole-brain radiation therapy, achieving durable remission exceeding 3 years. To our knowledge, this is the first reported case in the CNS setting, suggesting that DUSP22 rearrangement and ALK gain may confer a favorable prognosis. The authors have confirmed clinical trial registration is not needed for this submission.