question: Q:A 44-year-old man is brought to the emergency department by his daughter for a 1-week history of right leg weakness, unsteady gait, and multiple falls. During the past 6 months, he has become more forgetful and has sometimes lost his way along familiar routes. He has been having difficulties operating simple kitchen appliances such as the dishwasher and coffee maker. He has recently become increasingly paranoid, agitated, and restless. He has HIV, hypertension, and type 2 diabetes mellitus. His last visit to a physician was more than 2 years ago, and he has been noncompliant with his medications. His temperature is 37.2°C (99.0°F), blood pressure is 152/68 mm Hg, pulse is 98/min, and respiratory rate is 14/min. He is somnolent and slightly confused. He is oriented to person, but not place or time. There is mild lymphadenopathy in the cervical, axillary, and inguinal areas. Neurological examination shows right lower extremity weakness with normal tone and no other focal deficits. Laboratory studies show:
  Hemoglobin 9.2 g/dL
  Leukocyte count 3,600/mm3
  Platelet count 140,000/mm3
  CD4+ count 56/µL
  HIV viral load > 100,000 copies/mL
  Serum
  Cryptococcal antigen Negative
  Toxplasma gondii IgG Positive
  An MRI of the brain is shown below. Which of the following is the most likely diagnosis?? 
  {'A': 'Cerebral toxoplasmosis', 'B': 'Cryptococcal meningoencephalitis', 'C': 'HIV encephalopathy', 'D': 'Primary CNS lymphoma', 'E': 'Progressive multifocal leukoencephalopathy'},