Is it always cancer? A curious case of benign intracranial hypertension in chronic myeloid leukemia

28-year-old African American female with chronic myeloid leukemia (CML) presented with blurry vision for 4-5 days prior to presentation associated with right-sided headaches. Patient was on treatment for the CML but never had hematological remission. Patient saw an ophthalmologist who told her that she has bilateral optic disc swelling and advised her to get an MRI of the brain. She came to the ER due to worsening headache and blurry vision. The funduscopic examination showed significant bilateral papilledema. Laboratory evaluation revealed a leukocytosis of 240 × 103/uL with platelet count of 1,202 × 103. The white cell differential count showed 17% blasts along with myelocytes and meta-myelocytes. MRI of brain revealed non-specific CSF flair signal. Lumbar puncture (LP) showed significantly elevated opening pressures. The CSF composition was however normal. The patient felt much relief of her symptoms following the LP. The papilledema was thought to be due to benign intracranial hypertension (ICH), which was attributed to poor CSF absorption due to resistance to flow of CSF caused by the high WBC count. She received 2 cycles of leukopheresis which dropped her WBC count. She was also started on acetazolamide for the benign ICH and her symptoms improved considerably. Patients with CML can thus present with symptoms mimicking CNS involvement of the disease such as headaches and blurry vision, but that could be attributed to the poor CSF resorption given the leukocytosis rather than spread of the disease itself.