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Retired NBME 25 Answers

nbme25/Block 1/Question#47 (reveal difficulty score)
A 33-year-old woman with HIV infection is brought
Non-Hodgkin lymphoma ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags: hemeonc

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submitted by โˆ—shak360(19)
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Why is it not toxoplasmosis?

They took antibiotics meant for treating toxoplasmosis and they presented with only one lesion in the right cerebral cortex.


Congenital and immunocompromised toxoplasmosis

Chorioretinitis (inflammation of the retina and the choroid or the vascular tissue of the eye), diffuse intracranial calcifications, and hydrocephalus (indicated by ventriculomegaly) in a new born.

Caused by Toxoplasma gondii infection during pregnancy. Consumption of contaminated, undercooked pork. Can also be due to contact with contaminated cat feces.

In an immunocompromised patient, multiple ring-enhancing lesions within the subcortical white matter, basal ganglia, and/or thalamus are highly suggestive of cerebral toxoplasmosis. Toxoplasma gondii is an obligate intracellular parasite, contracted via ingestion of cysts in raw meat or oocysts in cat feces. In immunocompetent patients, the presentation is usually asymptomatic.

Cerebral toxoplasmosis is treated with a combination of sulfadiazine and pyrimethamine.

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shak360  See FA 2020 pp 177 on the common diseases of HIV-positive adults. At a CD4+ cell count of less than 100/mm3, EBV (HHV4) can present with B-cell lymphoma (that is, a non-Hodgkin's lymphoma such as a CNS lymphoma). In CNS lymphoma, it is ring-enhancing and most likely solitary. Whereas with Toxoplasma gondii, it would present with MULTIPLE ring-enhancing lesions. +



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submitted by โˆ—namesthegame22(13)
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Solitary brain lesions in patients with HIV/AIDS, particularly when associated with a low CD4+ count and a high viral load, should raise suspicion for primary CNS lymphoma.

DDX: bacterial abscess, (no infectious sx) cerebral toxoplasmosis, (she was treated) primary brain tumors, (not GBM in aids pt on nbme) and metastatic lesions. (multiple tumors)

AIDS pt with uncontrolled infxn = NHL.

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