Differentials
Central nervous system lymphoma
SIGNS / SYMPTOMS
There may be no difference in signs and symptoms, although fever may be less common.
INVESTIGATIONS
Brain biopsy. Usually a solitary lesion.
Metastatic brain lesions from primary malignancy
SIGNS / SYMPTOMS
There may be no difference in signs and symptoms.
INVESTIGATIONS
Brain biopsy. Evidence of malignancy on physical examination or body imaging.
Mycobacterial central nervous system disease
SIGNS / SYMPTOMS
Prior history of residence in an endemic area. May be history of chronic cough, weight loss, hemoptysis, and other signs of disseminated infection.
INVESTIGATIONS
Polymerase chain reaction of cerebrospinal fluid (CSF) for tuberculosis, mycobacterial culture of CSF, brain biopsy for acid-fast bacilli staining and culture, sputum stain and culture may be positive for acid-fast bacilli, and chest x-ray may show cavitations if pulmonary disease also present.
Aspergillosis
SIGNS / SYMPTOMS
Presence of pulmonary lesions in addition to central nervous system lesions more frequently seen in aspergillosis. Symptoms may include cough, chest pain, and hemoptysis.
INVESTIGATIONS
Cerebrospinal fluid fungal culture, galactomannan.
Cryptococcosis
SIGNS / SYMPTOMS
Symptoms may include cough, chest pain, and hemoptysis.
INVESTIGATIONS
Cryptococcal antigen from cerebrospinal fluid (CSF) and serum, CSF fungal culture.
Chagas disease
SIGNS / SYMPTOMS
Prior history of residence in an endemic area (Central and South America). Acute infection is rarely symptomatic, but acute infection in the very young (<2 years old) may present with encephalitis or focal brain lesions, often accompanied by myocarditis, and poses a high mortality risk. Chronic infections occasionally develop acute central nervous system involvement (encephalitis with necrotic brain lesions causing mass effect) in patients who are immunocompromised.
INVESTIGATIONS
Demonstration of Trypanosoma cruzi in blood, tissue or cerebrospinal fluid, polymerase chain reaction of tissue or body fluids, serologic tests.
Cytomegalovirus infection
SIGNS / SYMPTOMS
Most common central nervous system opportunistic infection in AIDS patients, presenting subacutely with encephalitis, retinitis, progressive myelitis, or polyradiculitis. In disseminated disease, may also include liver test abnormalities or worsening renal function.
INVESTIGATIONS
Brain CT/MRI/biopsy: location of lesions is usually near the brain stem or periventricular areas.
Polymerase chain reaction of cerebrospinal fluid with detectable virus is diagnostic.
Brain biopsy with positive staining for cytomegalovirus or evidence of owl's eyes is also diagnostic but is rarely performed due to the location of brain lesions.
Herpes simplex infection
SIGNS / SYMPTOMS
Seizures, headache, confusion, and/or urinary retention can be seen in disseminated disease, which usually affects only immunocompromised or acute infections in pregnant women; may be associated with concurrent genital/oral lesions; can be spread to the neonate during acute infection in the mother, or via viral shedding in the birth canal. Neonatal herpes simplex virus can range from localized skin infections to encephalitis, pneumonitis, and disseminated disease.
INVESTIGATIONS
Brain CT/MRI/biopsy: location of lesions is usually the medial temporal lobe or the orbital surface of the frontal lobe.
Polymerase chain reaction of cerebrospinal fluid with detectable virus is diagnostic.
Varicella zoster infection
SIGNS / SYMPTOMS
Multifocal involvement has a subacute course, usually only in people who are immunosuppressed, with headache, fever, focal neurologic deficits, and seizures. Unifocal involvement is more typically seen in people who are immunocompetent, occurring after contralateral cranial nerve herpes zoster, with mental status changes, transient ischemic attacks, and stroke. Disseminated varicella zoster virus can occur in adults during primary infection, presenting with pneumonitis and/or hepatitis.
INVESTIGATIONS
Disease is usually a vasculopathy, with hemorrhage and stroke.
Polymerase chain reaction of cerebrospinal fluid with detectable virus is diagnostic.
Bacterial abscess (including Nocardia spp.)
SIGNS / SYMPTOMS
May be associated with sinusitis (abutting the sinuses) or with bacteremia. Signs and symptoms are similar, including fever and necrotizing brain lesions with mass effect.
INVESTIGATIONS
Cerebrospinal fluid culture or culture of brain abscess.
Progressive multifocal leukoencephalopathy
SIGNS / SYMPTOMS
Symptoms are often more insidious in onset and progress over months. Symptoms include progressive weakness, poor coordination, with gradual slowing of mental function. Only seen in people who are immunosuppressed. Rarely associated with fever or other systemic symptoms.
INVESTIGATIONS
Polymerase chain reaction of cerebrospinal fluid for John Cunningham virus.
Biopsy reveals white matter lesions which are poorly circumscribed.
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