A 40-year-old man with known HIV infection comes to the emergency department with lethargy and right-sided weakness. He is accompanied by his girlfriend, who says that he has been behaving strangely for the past 3-4 weeks. He has also been complaining of headaches. The patient does not routinely follow up with his physician, and his last CD4 count 3 months ago was 50 cells/µL.
His temperature is 37.2° C (99° F), blood pressure is 140/80 mm Hg, pulse is 88/min, and respirations are 16/min. Pulse oximetry shows 96% on room air. The patient appears lethargic but follows commands. He has poor dentition and oral thrush. No neck stiffness is present. He has a pronator drift in the right upper extremity with slightly increased tone and brisk reflexes. The remainder of the examination is normal.
Diffusion-weighted magnetic resonance imaging of the brain with and without contrast reveals a large (4.2-cm) ring-enhancing deep subcortical white matter lesion with surrounding vasogenic edema and mass effect.
What is the most likely diagnosis in this patient?

Question

A 40-year-old man with known HIV infection comes to the emergency department with lethargy and right-sided weakness.  He is accompanied by his girlfriend, who says that he has been behaving strangely for the past 3-4 weeks.  He has also been complaining of headaches.  The patient does not routinely follow up with his physician, and his last CD4 count 3 months ago was 50 cells/µL.
His temperature is 37.2° C (99° F), blood pressure is 140/80 mm Hg, pulse is 88/min, and respirations are 16/min.  Pulse oximetry shows 96% on room air.  The patient appears lethargic but follows commands.  He has poor dentition and oral thrush.  No neck stiffness is present.  He has a pronator drift in the right upper extremity with slightly increased tone and brisk reflexes.  The remainder of the examination is normal.
Diffusion-weighted magnetic resonance imaging of the brain with and without contrast reveals a large (4.2-cm) ring-enhancing deep subcortical white matter lesion with surrounding vasogenic edema and mass effect.
What is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec193a_9645_ff77_853d_51d535322922_MD0002_00 This patient's presentation of severe immunosuppression, confusion, lethargy, hemiparesis, and MRI findings (large, ring-enhancing lesion with edema and mass effect) is most suggestive of primary central nervous system lymphoma (PCL). PCL occurs with advanced immunosuppression, such as CD4 counts < 50 cells/µL. Most patients present with confusion, motor deficits, aphasia, memory loss, and/or seizures. B symptoms such as fever, night sweats, and weight loss are present in about 80% of patients. In patients with AIDS, the differential diagnosis of CNS lesions that are ring-enhancing with edema and mass effect includes toxoplasma encephalitis and primary CNS lymphoma. Imaging features suggestive of PCL are solitary lesions, lesions > 4 cm, and those involving the corpus callosum, periventricular, or periependymal areas. Posterior fossa lesions are more suggestive of infection than PCL. Definitive diagnosis of PCL requires cerebrospinal fluid cytology, detection of Ebstein-Barr virus DNA in the cerebrospinal fluid, toxoplasma serologies, and/or brain biopsy. (Choice A) Cytomegalovirus encephalitis occurs in HIV patients with CD4 counts < 50 cells/µL who may present with confusion, dementia, delirium, and focal neurologic deficits. MRI usually reveals diffuse micronodular encephalitis or ventriculoencephalitis (periventricular inflammation). This patient's presentation and MRI findings are most suggestive of lymphoma. (Choice C) Patients with progressive multifocal leukoencephalopathy usually present with rapidly progressive neurologic deficits such as altered mental status, motor deficits, ataxia, aphasia, visual symptoms, and cognitive impairment. Suggestive MRI findings include asymmetric white matter lesions without enhancement, mass effect, or edema. (Choice D) Toxoplasma encephalitis occurs in HIV patients with CD4 counts < 100 cells/µL who are not on anti-toxoplasma prophylaxis. MRI findings may show multiple ring-enhancing lesions with mass effect and edema and a predilection for the basal ganglia. This patient's MRI findings of a solitary large lesion are more suggestive of lymphoma than toxoplasma encephalitis. Educational objective: In patients with AIDS, ring-enhancing central nervous system lesions with mass effect and edema are suggestive of primary central nervous system lymphoma (PCL) or toxoplasma encephalitis. Imaging features suggestive of PCL are solitary lesions, lesions > 4 cm, and those involving the corpus callosum, periventricular, or periependymal areas. Toxoplasma encephalitis should be suspected in patients with multiple ring-enhancing lesions and a predilection for the basal ganglia. __________ References: Use of CT and MR imaging to distinguish intracranial lesions and to define the need for biopsy in AIDS patients. (http://www.ncbi.nlm.nih.gov/pubmed/2213162) Primary CNS lymphoma in HIV positive and negative patients: comparison of clinical characteristics, outcome and prognostic factors. (http://www.ncbi.nlm.nih.gov/pubmed/20526793) Primary central nervous system lymphoma versus toxoplasmosis in AIDS. (http://www.ncbi.nlm.nih.gov/pubmed/2027999)

A 40-Year-Old Man with Known HIV Infection Comes to the Emergency