Abstract
Progressive multifocal leukoencephalopathy (PML) is a demyelinating brain disease caused by reactivation of JC virus in immunocompromised patients. PML typically manifests with subacute neurologic deficits including altered mental status, motor deficits, limb ataxia, gait ataxia, and visual symptoms. We report an atypical presentation of PML in a lung transplant recipient (LTR).
A 71-year-old LTR received rituximab induction followed by a combination of mycophenolate mofetil, tacrolimus, and prednisone. He had a single episode of minimal acute cellular rejection early after LT, but never required significantly augmented immunosuppression. Notably, he had mild leukopenia throughout his post-LT course (WBC count 3-4 thousand/µL), and he had no response to 4 doses of the Pfizer SARS-CoV-2 vaccine, suggesting advanced immunosuppression. At 14 months after LT, the patient reported progressive anomia and aphasia, but no other neurologic deficits. MRI showed an abnormal increased T2/FLAIR signal in the left posterior parieto-occipital subcortical white matter, involving subcortical U fibers, characteristic of PML (Figure A, C). Serum JC virus PCR showed low-level viremia, but CSF from 2 lumbar punctures was PCR negative. Thus, he was diagnosed with possible PML, and immunosuppression was narrowed to a combination of tacrolimus (goal trough 4-6) and prednisone, 5 mg daily. Despite reduced immunosuppression, a repeat MRI 2 months after the initial diagnosis showed worsening PML (Figure B, D) and his symptoms progressed to severe anomia, aphasia, and cortical blindness, but still no motor deficits.
PML is a rare, albeit well described, complication of LT, but presentation with only anomia and aphasia is unusual. Without CSF viral isolation, a definitive diagnosis requires brain tissue; however, MRI changes involving subcortical U fibers in the parieto-occipital area are highly characteristic. Early recognition allows for expeditious management.