Vision loss as the first manifestation of isolated cns relapse in CML blast crisis during flumatinib maintenance therapy: A case report.

RATIONALE: Central nervous system (CNS) involvement following blast crisis (BC) of chronic myeloid leukemia (CML) represents a challenging complication, particularly when atypical symptoms such as progressive vision loss obscure the diagnosis and delay timely intervention. PATIENT CONCERNS: A 65-year-old male presented with isolated CNS relapse following CML-BC, manifesting as progressive visual loss. Despite being in intramedullary complete remission and having received prophylactic intrathecal chemotherapy, the patient's atypical ocular symptom raised suspicion of CNS involvement. DIAGNOSES: Cerebrospinal fluid (CSF) analysis confirmed the presence of blast cells, establishing the diagnosis of CNS relapse. INTERVENTIONS: Treatment with intrathecal chemotherapy, systemic high-dose chemotherapy combined with tyrosine kinase inhibitor therapy. OUTCOMES: The patient demonstrated visual recovery and sustained disease remission at the 14-month follow-up. LESSONS: This case underscores the importance of clinical vigilance in patients with a history of leukemia who present with blurred vision or progressive vision impairment, as such manifestations,even in the absence of overt neurological symptoms, may be indicators of CNS relapse. Additionally, further investigation through animal models is warranted to characterize the blood-brain barrier penetrance of novel tyrosine kinase inhibitors (TKIs).