A 35-year-old man comes to the office due to 4 weeks of generalized malaise, left-sided headache, and weakness of the right hand. The patient has a history of intravenous drug use, which led to hepatitis C and HIV infections. He has refused antiretroviral therapy, and his last known CD4 count was 298/mm³ 3 months ago. He has never had an HIV-related opportunistic infection or been hospitalized.
Temperature is 37.2 C (99 F) , blood pressure is 110/70 mm Hg, and pulse is 106/min. Examination shows no oral thrush or enlarged lymph nodes. Erythematous macules are present on both palms. A 3/6 holosystolic murmur is heard at the cardiac apex. The lungs are clear to auscultation. The abdomen is nontender. There are no meningeal signs. Motor strength is 4/5 in the right upper extremity and 5/5 in the remaining extremities. Reflexes are 3+ in the right upper extremity with a noted extensor plantar response on the right.
Laboratory results are as follows:
CT scan of the head with and without contrast reveals a 2.4-cm, ring-enhancing, round mass with vasogenic edema and mild mass effect at the grey-white matter junction in the left frontal lobe.
Which of the following is the most likely diagnosis?

Question

A 35-year-old man comes to the office due to 4 weeks of generalized malaise, left-sided headache, and weakness of the right hand. The patient has a history of intravenous drug use, which led to hepatitis C and HIV infections. He has refused antiretroviral therapy, and his last known CD4 count was 298/mm³ 3 months ago. He has never had an HIV-related opportunistic infection or been hospitalized.
Temperature is 37.2 C (99 F) , blood pressure is 110/70 mm Hg, and pulse is 106/min. Examination shows no oral thrush or enlarged lymph nodes. Erythematous macules are present on both palms. A 3/6 holosystolic murmur is heard at the cardiac apex. The lungs are clear to auscultation. The abdomen is nontender. There are no meningeal signs. Motor strength is 4/5 in the right upper extremity and 5/5 in the remaining extremities. Reflexes are 3+ in the right upper extremity with a noted extensor plantar response on the right.
Laboratory results are as follows:

CT scan of the head with and without contrast reveals a 2.4-cm, ring-enhancing, round mass with vasogenic edema and mild mass effect at the grey-white matter junction in the left frontal lobe.
Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_988c_6cab_853d_69bc1dfd75c4_MD0002_00 This patient with subacute headache, neurologic symptoms, and a single ring-enhancing lesion at the grey-white matter junction most likely has a brain abscess. Single brain abscess usually results from direct extension from a dental, sinus, or ear infection; hematogenous dissemination from a distant infection tends to cause multiple abscesses but can occasionally lead to single abscess. This patient's intravenous drug use, holosystolic murmur, and Janeway lesions (erythematous macules on the palms) suggest that his single abscess may be due to underlying infectious endocarditis. Brain abscess is usually the result of Streptococcus or Staphylococcus infection, but patients with HIV are susceptible to a wider range of bacterial (eg, Listeria, Nocardia), fungal (eg, Aspergillus, Cryptococcus), and parasitic (eg, Toxoplasma) organisms. Symptoms tend to be nonspecific and insidious and often include unilateral headache localized to the side of the lesion, focal neurologic deficits, seizures, or papilledema. Fever and leukocytosis are frequently absent, particularly in those with underlying immunosuppression. CT scan with and without contrast typically reveals single or multiple ring-enhancing lesions at the grey-white matter junction with significant vasogenic edema or mass effect. Treatment with antibiotics and surgical drainage is usually curative, but many patients are left with residual seizure disorder. Patients with HIV can also develop ring-enhancing lesions due to: Toxoplasmic encephalitis - typically causes multiple ring-enhancing lesions in the basal ganglia and frontal/parietal lobes and almost always occurs in patients with CD4 counts <100/mm³ (unlike this patient) who have positive toxoplasma IgG serology and are not on chemoprophylaxis (Choice E)Primary central nervous system lymphoma - typically appears as a single, large (>4 cm), ring-enhancing lesion in the subcortical white matter and almost always occurs in patients with CD4 counts <50/mm³ (Choice C) Toxoplasmic encephalitis - typically causes multiple ring-enhancing lesions in the basal ganglia and frontal/parietal lobes and almost always occurs in patients with CD4 counts <100/mm³ (unlike this patient) who have positive toxoplasma IgG serology and are not on chemoprophylaxis (Choice E) Toxoplasmic encephalitis - typically causes multiple ring-enhancing lesions in the basal ganglia and frontal/parietal lobes and almost always occurs in patients with CD4 counts <100/mm³ (unlike this patient) who have positive toxoplasma IgG serology and are not on chemoprophylaxis (Choice E) ³ Primary central nervous system lymphoma - typically appears as a single, large (>4 cm), ring-enhancing lesion in the subcortical white matter and almost always occurs in patients with CD4 counts <50/mm³ (Choice C) Primary central nervous system lymphoma - typically appears as a single, large (>4 cm), ring-enhancing lesion in the subcortical white matter and almost always occurs in patients with CD4 counts <50/mm³ (Choice C) ³ (Choice B) HIV-associated encephalopathy generally affects the whole brain and presents with progressive dementia. Patients tend to have brain atrophy without ring-enhancing lesions on imaging. (Choice D) Progressive multifocal leukoencephalopathy is a rapidly progressive demyelinating disorder due to JC virus reactivation that usually occurs in patients with CD4 counts <200/mm³. Brain imaging usually reveals multifocal areas of white matter demyelination with no mass effect, edema, or enhancement. ³ Educational objective: Brain abscess is usually characterized by single or multiple ring-enhancing lesions at the grey-white matter junction with significant vasogenic edema or mass effect. Toxoplasmosis usually causes multiple ring-enhancing lesions in the basal ganglia and frontal/parietal regions and almost always occurs in those with HIV who have CD4 counts <100/mm³ and positive toxoplasma IgG serology. Primary central nervous system lymphoma usually occurs in the subcortical white matter and is most common in those with HIV who have CD4 counts <50/mm³. ³ ³ __________ References: Brain abscess: an overview. (http://www.ncbi.nlm.nih.gov/pubmed/21087684) Opportunistic infections of the CNS in patients with AIDS: diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/12962527)

A 35-Year-Old Man Comes to the Office Due to 4