Thread by @ID_fellows

1/ Happy Opportunistic Monday #IDtwitter #IDfellows! Here is another interesting learning case for you all. Written by @KrutiYagnikDO and @johnhannamd

2/ While awaiting pending work-up, what is the best next step?

3/ #IDpearls

Major differential in this newly diagnosed HIV patient, presenting with brain ring enhancing lesions:

-CNS toxoplasmosis
-Primary CNS lymphoma (usually EBV+)
-TB
-Cryptococcus
-brain abscess
-Nocardia
-Chagas (given visit to Peru)
-Malignancy

4/ Other differential for CNS involvement (usually white matter disease) in HIV patients with CD4<200 includes PML, CMV encephalitis, histoplasma, and HIV encephalopathy.

5/ LP would be helpful for diagnosis; however, this would be contraindicated in this case due to midline shift.

When unable to obtain CSF: A trial of empiric toxoplasma therapy vs stereotactic brain biopsy is considered.

6/ In patients with CNS toxoplasmosis from reactivation (if CD4 <100), serum Toxoplasma IgG is typically positive.

However, cases of CNS toxo with negative IgG are reported.

Positive toxo PCR from CSF (when obtained) or histological pathology can confirm diagnosis.

7/ CSF Toxo PCR is very specific (positive confirms diagnosis)

But has limited sensitivity (negative does not R/O)

pubmed.ncbi.nlm.nih.gov/8958252/

8/ A presumptive toxo encephalopathy (TE) diagnosis can be made when:

CD4 <100
& Not on Toxoplasma ppx
& Compatible clinical presentation
& Positive Toxoplasma IgG
& MRI brain with ring enhancing lesions

9/ SPECT CT scan is another imaging test that can help differentiate between TE and CNS lymphoma.

See study from @Parkland pubmed.ncbi.nlm.nih.gov/10908023/

10/ Treatment regimen of choice: Sulfadiazine, pyrimethamine & leucovorin + ART (when possible)

Alternatives: Pyrimethamine (frequently limited use by high cost) + clindamycin vs TMP/SMX.

Initial Duration: 6 weeks followed by chronic maintenance at lower doses.

11/ Toxoplasma-seropositive patients who have CD4 counts <100 should receive prophylaxis with TMP-SMX or atovaquone. Note- Dapsone does not cover toxoplasma.

Prophylaxis against TE should be discontinued in patients receiving ART with CD4 >200 for more than 3 months

12/ ART is preferred to start within the first 2 weeks.

In our patient, given recent travel to Peru with TB on differential, we preferred to hold ART initially to rule out active TB and avoid potential TB IRIS.

13/ Patient’s clinical course:

-Serum toxo IgG was +
-IGRA -, serum crypto ag -
-CD4 count resulted at 22/4.5%

Repeat brain MRI in 2 weeks with significant improvement in lesions while on Pyrimethamine, sulfadiazine & leucovorin, along with clinical improvement.

14/ See this amazing OI algorithm @BradCutrellMD

15/ Case written by @johnhannamd and @KrutiYagnikDO

Case reviewed by @BradCutrellMD