Toxoplasmosis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Toxoplasmosis manifests as a painless lymphadenopathy in an immunocompetent individual. In patients with AIDS and other immunocompromised conditions, it mainly involves brain and presents with fever and focal neurological symptoms. The major differential diagnosis of focal CNS lesions in patients with AIDS is CNS lymphoma, which manifests as multiple enhancing lesions in 40% of cases. Other differentials in the diagnosis of toxoplasmosis include brain abscess, cytomegalovirus, herpes simplex, histoplasmosis, infectious mononucleosis, listeria monocytogenes infection (Listeriosis), lymphoblastic lymphoma, metastatic cancer with unknown primary site.

Differential Diagnosis

Toxoplasmosis manifests as a painless lymphadenopathy in an immunocompetent individual. In patients with AIDS and other immunocompromised conditions, it mainly involves brain and presents with fever and focal neurological symptoms. The major differential diagnosis of focal CNS lesions in patients with AIDS is CNS lymphoma, which manifests as multiple enhancing lesions in 40% of cases. Other differentials in the diagnosis of toxoplasmosis include brain abscess, cytomegalovirus, herpes simplex, histoplasmosis, infectious mononucleosis, listeria monocytogenes infection (Listeriosis), lymphoblastic lymphoma, metastatic cancer with unknown primary site.

Disease	Differentiating signs and symptoms	Differentiating tests
CNS lymphoma	Immunocompetent individual Focal symptoms indicative of a mass lesion Seizure	Single solitary ring enhacning lesion on CT or MRI
Disseminated tuberculosis	Prior history of residence in an endemic area. Chronic cough, weight loss, hemoptysis	PCR of CSF for tuberculosis Mycobacterial culture of CSF Brain biopsy for acid-fast bacilli staining Culture and acid stain positive for acid-fast bacilli CXR shows cavitations.
Aspergillosis	Pulmonary lesions in addition to CNS lesions. Symptoms may include cough, chest pain, and hemoptysis.	CSF fungal culture, galactomannan.
Cryptococcosis	Symptoms include cough, chest pain, and hemoptysis	Cryptococcal antigen from CSF and serum CSF fungal culture
Chagas disease	History of residence in Central and South America Acute infection is rarely symptomatic, Encephalitis or focal brain lesions Myocarditis Chronic infections in immunocompromised patients develops into encephalitis with necrotic brain lesions causing mass effect.	Trypanosoma cruzi in blood, tissue or CSF, PCR of tissue or body fluids, serologic tests.
CMV infection	Most common CNS opportunistic infection in AIDS patients Presents with encephalitis, retinitis, progressive myelitis or polyradiculitis. In disseminated disease, it involves both liver and renal organs.	Brain CT/MRI/biopsy: location of lesions are usually near the brain stem or periventricular areas. PCR of CSF with detectable virus is diagnostic. Brain biopsy with + staining for CMV or evidence of owl's eyes is also diagnostic, but it is rarely performed, because of the location of brain lesions.
HSV infection	Seizures, headache, confusion and/or urinary retention can be seen in disseminated disease, which usually affects only immunocompromised or acute infections In pregnant women it 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 HSV can range from localized skin infections to encephalitis, pneumonitis, and disseminated disease.	Brain CT/MRI/biopsy: location of lesions is usually the medial temporal lobe or the orbital surface of the frontal lobe. PCR of CSF with detectable virus is diagnostic.
Varicella Zoster infection	Multifocal involvement has subacute course, usually only in immunosuppressed, with headache, fever, focal deficits, and seizures. Unifocal involvement is more typically seen in immunocompetent hosts, occurring after contralateral cranial nerve herpes zoster, with mental status changes, TIAs, and stroke. Disseminated varicella zoster virus can occur in adults during primary infection, presenting with pneumonitis and/or hepatitis. Disease is a vasculopathy, with hemorrhage and stroke.	PCR of CSF with detectable virus is diagnostic.
Brain abscess	Associated with sinusitis (abutting the sinuses) or with bacteremia. Signs and symptoms includes fever and necrotizing brain lesions with mass effect	CSF culture or culture of brain abscess.
Progressive multifocal leukoencephalopathy	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 the immunosuppressed. Rarely associated with fever or other systemic symptoms.	PCR of CSF for JC virus. Biopsy reveals white matter lesions and not well-circumscribed lesions.

References

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