Acute Myeloid Leukemia Relapse Presenting as Complete Monocular Vision Loss due to Optic Nerve Involvement.

Acute myeloid leukemia (AML) involvement of the central nervous system is relatively rare, and detection of leptomeningeal disease typically occurs only after a patient presents with neurological symptoms. The case herein describes a 48-year-old man with relapsed/refractory AML of the mixed lineage leukemia rearrangement subtype, who presents with monocular vision loss due to leukemic eye infiltration. MRI revealed right optic nerve sheath enhancement and restricted diffusion concerning for nerve ischemia and infarct from hypercellularity. Cerebrospinal fluid (CSF) analysis showed a total WBC count of 81/mcl with 96% AML blasts. The onset and progression of visual loss were in concordance with rise in peripheral blood blast count. A low threshold for diagnosis of CSF involvement should be maintained in patients with hyperleukocytosis and high-risk cytogenetics so that prompt treatment with whole brain radiation and intrathecal chemotherapy can be delivered. This case suggests that the eye, as an immunoprivileged site, may serve as a sanctuary from which leukemic cells can resurge and contribute to relapsed disease in patients with high-risk cytogenetics.