Case15

Background


A 35-year-old woman was referred to Johns Hopkins Hospital, Baltimore, Maryland, for a brain biopsy. The patient initially presented to a local community hospital following 5 days of blurred vision associated with headache and 2 days of left face, arm, and leg numbness. These symptoms had come on gradually, were becoming progressively worse, and were accompanied with generalized fatigue and anxiety. She also complained of a dry cough and dyspnea on exertion. She denied any fever, chills, night sweats, or weight loss. She reported no contacts with other sick individuals and no recent travel outside her hometown. She did not own any pets.

The patient had diabetes mellitus type 2. She had undergone a hysterectomy a few years earlier for cervical cancer. She also had been diagnosed with pulmonary alveolar proteinosis (PAP).She lived with her husband; they had no children. She reported a 20-year, 2-packs-per-day smoking history, but had recently cut down to 1 pack per day. She denied any alcohol or illicit drug use.Her family members were known to have coronary artery disease, hypertension, and diabetes.
The patient's initial physical exam from the local hospital was not available. She reported that she did not have a fever, and although her left side felt numb and heavy, she was able to walk.
Initial Laboratory Studies
White blood cell count: 9.7 x 103 cells/mm3.
Hematocrit: 43%.
Platelets: 256,000 cells/mL.
Na: 137 mEq/L.
K: 3.9 mEq/L.
BUN: 16 mg/dL.
Creatinine: .6 mg/dL.
Albumin: 3.6 g/dL.
Protein: 7 g/dL.
Alkaline phosphatase: 67 IU/L.
AST: 12 IU/L.
ALT: 36 IU/L.
The patient underwent head computed tomography (CT) and magnetic resonance imaging (MRI) of the brain. These showed multiple, bilateral lesions with surrounding edema on fluid-attenuated inversion recovery (FLAIR) images (Figure 1), which appeared ring-enhancing on postgadolinium images.

Which of the following would be the least likely cause of ring-enhancing brain lesions in an immunocompetent patient?

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