A 19-year-old lady presents to your Clinic complaining of transient loss of consciousness and right arm pain while washing clothes. She is unable to recall the amount of time she lost consciousness but stated that she was at her baseline mental status when her grandmother returned home one hour later. She states that she has had no chest pain, palpitations, abdominal pain, or vertigo prior to the event. She had noticed fatigue and headaches for two weeks. The patient describes her arm pain as an intermittent cramping sensation that had been present for around forty-eight hours. In the past, the patient has been generally in good health, apart from repeated episodes of upper respiratory tract infections during childhood. The patient has never been tested for HIV infection. Her mother died when she was 2 years old, but she does not know the cause of death. Physical examination reveals a young woman in no apparent distress who is alert and oriented to name, place and time. Temperature is 37.6 °C, blood pressure 120/80 mm Hg, pulse 88 beats/min, respirations 17 breaths/min, and oxygen saturation of 98% on room air.

She has equal and reactive pupils, a normal oropharyngeal exam, supple neck without pain on range of motion, clear lung fields, a normal cardiac and abdominal exam, and normal extremities. Her skin does not show any signs of a rash or stigmata of chronic liver disease. Neurologic testing reveals a right homonymous hemianopsia, normal strength, deep tendon reflexes, and sensation bilaterally. Her gait is steady and she has a normal cerebellar exam.

You decide to send the patient for Neurology consultation to a Referral Hospital, where a lumbar puncture and blood tests are performed.

Results of CSF (cerebrospinal fluid) examination

WBC 105/µL (71% lymphocytes, 29% monocytes, 0 polymorphonuclear cells); 0 red blood cells; Proteins 176 mg/dL (normal <45); Glucose 21 mg/dL (normal 50-80).

Results of HIV assays and CD4 cell count

HIV-Ab rapid test: POSITIVE

HIV-RNA PCR: 760,000 copies/mL

CD4 cell count: 15/μL (3% of total lymphocytes)

Please answer the following questions:

1. On the basis of symptoms and test results, what is the MOST LIKELY diagnosis?

2. Which tests would you do on the cerebrospinal fluid to confirm the diagnosis?

3. What are the possible other diagnoses, considering the symptoms and the HIV status, and how you would confirm/disprove those?