A Rare Stroke Mimic in Acute Lymphocytic Leukemia

A 19-year-old man with a history of B-cell acute lymphocytic leukemia on combination chemotherapy (vincristine, daunorubicin, cyclophosphamide, cytarabine, and intravenous and intrathecal methotrexate) was admitted with a history of sudden onset slurring of speech for 2 days and right-sided weakness for 12 hours. There was no vomiting, blurred vision, fever, neck pain, double vision, or sensory disturbance. Examination showed mild distal weakness in the right upper and lower limbs with an extensor plantar response on the right side. He was admitted with a suspicion of acute stroke. Blood investigations, including complete blood count, erythrocyte sedimentation rate, blood glucose, and coagulation profile, were normal. MRI brain showed a diffusion-restricting, non-enhancing lesion in the left frontal subcortical region [Figure 1]. The differential diagnoses considered were stroke, demyelination, and toxic leukoencephalopathy. The sparing of gray matter and lack of a typical vascular distribution were pointers against an ischemic stroke. While progressive multifocal leukoencephalopathy (PML) is a demyelinating illness that can occur in this clinical setting, the characteristic radiological features (multifocal lesions with subcortical U fiber involvement and peripheral patchy diffusion restriction) were absent. Hence, a diagnosis of methotrexate-induced stroke-like leukoencephalopathy was made. He was treated with high-dose folinic acid and completely recovered in 48 hours.Figure 1: Axial DWI (a) and corresponding ADC map (b) demonstrating a well-circumscribed lesion with diffusion restriction in the left corona radiata appearing hyperintense on FLAIR (c) and having no contrast enhancement (d)Intrathecal and high-dose intravenous methotrexate are known to be neurotoxic. Subacute methotrexate neurotoxicity commonly presents with seizures, stroke-like symptoms, or ataxia.[1] While diffusion restriction is often seen in these cases, the lesions characteristically spare the cortex and may not respect vascular territories.[2] While spontaneous recovery is the rule, treatment options include folinic acid and aminophylline.[3] A recent study showed that methotrexate rechallenge is safe in the majority of cases, with recurrence of neurotoxicity being rare and reversible.[4] As many of these patients have malignancy-related coagulopathies or blood dyscrasias, it is imperative to identify this stroke mimic in order to avoid inappropriate thrombolytic or antiplatelet therapy. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.