Objective:

NA

Background:

Progressive multifocal encephalopathy (PML) is a rare disorder nearly exclusively seen in immunocompromised patients or patients treated with immunosuppressive medications. The mainstay of treatment is to address the immunosuppressed state, by treating underlying disease or removing the offending drug. In cases where there has been no way to address the immunocompromise (as in ongoing cancer), there is limited data on treatment options.

Design/Methods:

NA

Results:

A 65-year-old woman initially presented for subacute onset of aphasia and confusion over 1 week.  MRI showed bilateral peripherally enhancing lesions of frontal lobes, left greater than right.  Basic labs were normal, and CSF showed positive oligoclonal bands and elevated myelin basic protein.  She had no response to IV steroids, and clinically declined to being completely non-verbal and hypoactive.  Repeat MRI demonstrated worsening of lesions.  Biopsy of the largest left frontal lesion was completed, and preliminary pathology was suggestive of viral process.  JC virus was identified by PCR in the serum and CSF, and pathology confirmed active JC virus in the lesion.  Her only prior medical history was well controlled diabetes, hypertension, hypothyroidism, and bipolar disorder.  Extensive work-up for underlying immunosuppression or malignancy was unrevealing.  Based on review of available case series, she was treated with pembrolizumab 200 mg every 3 weeks, with the first dose given in hospital.  At 2 month follow up she was discharged from rehab and speaking, and at 4 month follow up she was ambulating and back to baseline.  Treatment was stopped at 6 months, and at 10 months the patient has achieved sustained response.

Conclusions:

PML should remain in the differential for immunocompetent patients, and lesions in immunocompetent often present with greater than expected enhancement.  When identified, pembrolizumab should be considered as a possible treatment option.