A 21-year-old man is brought to the emergency department by his family after a witnessed generalized tonic-clonic seizure. His sister says that the patient has never had a previous seizure but has had progressive headaches, fever, nasal congestion, and rhinorrhea over the last 3 weeks. He has no chronic medical problems and does not use alcohol, tobacco, or illicit drugs. Temperature is 38.9 C (102 F), blood pressure is 130/85 mm Hg, and pulse is 96/min. The patient is drowsy and postictal. CT scan of the head with intravenous contrast reveals a 3-cm ring-enhancing lesion in the left frontal lobe. There are air-fluid levels and mucosal edema in the paranasal sinuses. Rapid HIV testing is negative. Tissue biopsy of the brain lesion is most likely to demonstrate which of the following?

Question

A 21-year-old man is brought to the emergency department by his family after a witnessed generalized tonic-clonic seizure.  His sister says that the patient has never had a previous seizure but has had progressive headaches, fever, nasal congestion, and rhinorrhea over the last 3 weeks.  He has no chronic medical problems and does not use alcohol, tobacco, or illicit drugs.  Temperature is 38.9 C (102 F), blood pressure is 130/85 mm Hg, and pulse is 96/min.  The patient is drowsy and postictal.  CT scan of the head with intravenous contrast reveals a 3-cm ring-enhancing lesion in the left frontal lobe.  There are air-fluid levels and mucosal edema in the paranasal sinuses.  Rapid HIV testing is negative.  Tissue biopsy of the brain lesion is most likely to demonstrate which of the following?

Quizplus · Accepted Answer

11ec25c8_d47d_bdae_bc81_7dbeebd1c118_MD0003_00 A single brain abscess is usually the result of direct extension from an adjacent tissue infection (eg, otitis media, sinusitis, dental infection). The 2 most commonly isolated organisms are viridans streptococci and Staphylococcus aureus. Symptoms are often nonspecific, which may delay diagnosis. Patients frequently have headaches that are severe, unilateral, and resistant to analgesics. Fevers are an unreliable predictor, occurring in ~50% of patients. If diagnosis is delayed, focal neurologic deficits or seizures may emerge. Brain imaging (CT scan, MRI) typically reveals cerebritis initially, but within 1-2 weeks the infection consolidates to a ring-enhancing lesion with central necrosis. Diagnosis requires CT-guided aspiration or surgical biopsy to obtain tissue for Gram stain and culture (bacterial, fungal, mycobacterial). Most patients are treated with empiric, intravenous antibiotics (eg, metronidazole, ceftriaxone, and vancomycin) and aspiration of the lesion. ring-enhancing lesion This patient with rhinorrhea, nasal congestion, and CT scan evidence of air fluid levels/edema in the paranasal sinuses likely had sinusitis that progressed to a brain abscess (seizure, single ring-enhancing lesion). (Choice A) Herpes encephalitis usually causes acute symptoms of altered mental status, focal deficits, and/or focal seizures. CT scan of the brain often reveals hypodense lesions in the temporal lobe. Ring enhancement is uncommon. (Choice B) A primary brain neoplasm (eg, lymphoma, glioblastoma) or metastasis could cause a seizure and a single ring-enhancing lesion on contrast CT scan. However, a young patient with fever and several weeks of sinusitis manifestations is more likely to have a brain abscess. (Choice C) Nocardia may cause a brain abscess with ring-enhancing lesions on CT scan. Most infections occur in patients with significant immunocompromise (eg, HIV with CD4 count <100/mm³). In this healthy young patient with ongoing sinusitis, a brain abscess with viridans streptococcus is far more likely. (Choice D) Rhizopus causes mucormycosis, which may spread from the sinuses through bone into the brain. Lesions tend to be necrotic and highly destructive; a single ring-enhancing lesion would be uncommon. In addition, most infections occur in patients with poorly controlled diabetes mellitus or significant immunocompromise (eg, chronic glucocorticoids). (Choice E) Cerebral toxoplasmosis is usually seen in patients with HIV with CD4 counts <100/mm³. Manifestations include headache, fever, confusion, focal neurologic deficits, and/or seizures. Multiple (not single) ring-enhancing lesions are typical. Educational objective: A single brain abscess usually results from direct extension of an adjacent infection (eg, otitis media, sinusitis, dental infection). Viridans streptococcus and Staphylococcus aureus are the 2 most commonly isolated organisms. Headache, fever, focal neurologic deficits, and seizure may be present. Brain imaging (CT scan, MRI) typically reveals a single ring-enhancing lesion with central necrosis. References: Clinical characteristics and outcome of brain abscess: systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/24477107)

A 21-Year-Old Man Is Brought to the Emergency Department by His