NBME 20 Non-Hodgkin lymphoma (NBME Answers)

NBME 20 Answers

nbme20/Block 4/Question#7 (reveal difficulty score)
A 33-year-old woman with HIV infection is ...
Non-Hodgkin lymphoma 🔍 / 📺 / 🌳 / 📖
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submitted by ∗hayayah(1212)

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This is a primary central nervous system lymphoma. Most commonly associated with HIV/AIDS; pathogenesis involves EBV infection.

Considered an AIDS-defining illness. Variable presentation: confusion, memory loss, seizures. Mass lesion(s) (may be ring-enhancing in immunocompromised patient) on MRI, needs to be distinguished from toxoplasmosis via CSF analysis or other lab tests. Toxo usually has multiple ring enhancing lesions.

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peridot For those who are curious, this is on p.422 of FA2019 +1

sofkha11 p. 430 FA2020 +

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submitted by ∗radion(21)

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Single enhancing lesion points more towards lymphoma than toxo. Toxo is usually multi-ring enhancing lesions.

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+4 upvote downvote
submitted by ∗yotsubato(1208)

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It cant be Bacterial abscess (Nocardia) because shes taking TMP SMX.

It cant be toxo, because she has one lesion and is also taking TMP SMX which should improve her symptoms.

Glioblastoma is a disease of older individuals

Metastatic disease that mets to the brain is unlikely at this age.

CNS lymphoma is common in HIV AIDS patients, so that is the most likely choice.

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mrglass She's not taking TMP/SMX though. I would pick lymphoma over abscess mainly because .5cm growth in 2 weeks is incredibly rapid, which is classic for diffuse B-cell lymphoma, which is what tends to be in the CNS. Also there was no evidence of a classic source of brain abscess like mastoiditis. +26

srmtn it is not difusse B cell lymph. is primary central nervous system Lymphoma. AIDS, Toxoplasma like image in MRI with no response to treatment, seizures, etc. FA 2019 p 422 +

cuddz According to UWorld 2083: PCNSL is a diffuse large-cell non-Hodgkin Lymphoma of B-cell origin (and thus composed of abnormal B-lymphocytes). It is the 2nd most common cause of ring-enhancing lesions with mass effect in HIV and occurs as a late complication of it. Large, solitary lesions are more likely to suggest PCNSL, but multiple lesions can occur as well. EBV is almost always identified via PCR. Although EBV is commonly a/w abnormal T-lymphocytes, T cell infiltration is not commonly seen in PCNSL, rather they are the malignant cells in AIDS-Associated T-Cell lymphoma +1

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