A thirty-nine-year-old African American female with no significant past medical history presented to the emergency department cachectic and "feeling sick" for two weeks with generalized fatigue, malaise, and productive cough with hemoptysis. Review of systems was positive for anorexia, unquantified weight loss, nausea, vomiting, and dizziness. She had no history of hypertension, hematologic disorders, or cancers in herself or in her family. 
The clinical examination at the time of admission revealed severe pallor and oral candidiasis with the rest of the examination benign. Her mental status was normal and she was alert and oriented to person, place, and time. Medical research scale (MRC) grade was 4/5 in all extremities, likely secondary to deconditioning and severe anemia. The patient's vital signs were normal, including a blood pressure of 122/65 mm Hg.
On admission, laboratory analysis revealed severe abnormalities including blood urea nitrogen (BUN) of 138 mmol/L, serum creatinine of 22.3 mumol/L, hemoglobin of 4.9 g/dL, and hematocrit of 16.4% with a normocytic anemia. Arterial blood gas revealed pH 7.17, pCO2 18.8 mm Hg, pO2 143 mm Hg, and oxygen saturation of 99 percent on room air. The other laboratory parameters including white blood count, chemistry panel, platelets, and liver function tests were within normal limits. Urine toxicology screen and pregnancy tests were negative.
She was admitted to the intensive care unit and placed on droplet precautions until tuberculosis was ruled out. She was given 4 units of packed red blood cells after ruling out reversible causes of blood loss. Gynecologic history included eleven live births with poor antenatal care. During the hospital stay, the patient was diagnosed, for the first time, with new onset ESRD classified as Stage 5 chronic kidney disease. It had gone unchecked and the patient was unaware of any kidney issues. During this admission, She received multiple rounds of dialysis which brought her blood urea nitrogen and creatinine ratio (BUN/Cr) to near normal ranges over 3 days. Also, due to the patient's oral candidiasis her HIV status was checked. HIV ELISA and Western Blot were positive with a CD4 T lymphocyte count of 112 cells/muL and a viral load of 780,000 cells/mm3. 
The patient was stable for the first 4 days until she had 2 seizures within 24 hours and became nonverbal, uncooperative, and encephalopathic. By this point, her BUN/Cr was brought down to 25/6.2 from the rounds of dialysis. Her blood pressure during the period of seizure was 152/96 mm Hg, which was thought to be secondary to the seizures, and electrolytes were within normal limits. She responded to painful stimuli, pupils were equally reactive, deep tendon reflexes intact, MRC rated 3/5, and there was no papilledema or neck stiffness. Keppra was started for seizure control. 
Computed tomography (CT) without contrast showed white matter hypodensity in the posterior parietal-occipital lobes with the remaining findings within normal limits (Figure 1). A CT performed the following day confirmed the presence of hypodense regions but with newly noted small hemorrhages within the parietal and occipital regions. Magnetic resonance imaging (MRI) without contrast revealed areas of T2 prolongation in the subcortical white matter, predominantly in the occipital and parietal regions with scattered foci of susceptibility artifact bilaterally in the occipital lobes. The largest focus measured 10 cm x 0.6 cm in the left occipital lobe (Figure 2). A repeat MRI with gadolinium showed a stable image with no pathologic enhancement and the foci of hemorrhage remained stable (Figure 3).
Given that PRES is a diagnosis of exclusion and based on clinical and radiographic findings, infectious causes of this acute change in mental status were ruled out. Cerebrospinal fluid analysis showed protein of 164 mg/dL, glucose of 49 mg/dL, 630 RBCs/mm3, 0 WBCs/mm3, and LDH of 37 U/L. No acid fast bacilli were seen. Polyomavirus, herpes simplex virus 1 and 2, cytomegalovirus, Epstein-Barr virus, Toxoplasma Gondii IgG, and VDRL were negative. Two sets of blood and urine cultures were negative. There were no further complications with mental status and her cognitive function recovered completely. The patient's vital signs, hemoglobin, and BUN/Cr were stable when she was discharged to home with follow up at the HIV and renal clinics.