A 60 year-old male with history of myelodysplastic syndrome who underwent Allogenic Matched Unrelated Donor Stem Cell transplant 35 days prior now presents from clinic with new confusion. The patient engrafted 8 days prior (Day 27) and course was complicated only by mild graft vs host disease. His medications include tacrolimus and prednisone. Family describes the patient as “foggy”: forgetting tasks in middle of completion, and not remembering conversations or events like meals. Also mood seemed irritable and “out of character”. The patient had no problems with long term memory.
ID was consulted 24 hours into admission after patients confusion progressed to somnolence. Serum cell counts consistent with recent engraftment ANC -1800.
CSF with WBC -10 (90% lymph), Protein 75, RBC 0, Protein 75 MRI Brain
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Correct Answer: HHV-6 PCR from CSF
The clinical presentation of HHV-6 encephalitis is described in a patient following Stem Cell Tx.
- HHV-6 or Roseola infects most in childhood and establishes latency.
- Viremia is common post stem cell transplant (30-70% depending on series) but clinical encephalitis as described in this case is rare.
- Syndrome is called Post-transplant acute limbic encephalitis (PALE) and often includes anterograde amnesia, personality changes and MRI with enhancement in amygdala/ hippocampus as seen in this case. Often will also have temporal lobe seizure activity.
- The case highlights typical timing (3-6 weeks post-transplant)
- CSF pattern typical with mild elevation in protein and lymphocytes.
Distractor answer choices
- PRES may present as confusion in patients on calcineuron inhibitors (tacrolimus). However PRES often has concurrent headache and seizures. MRI changes involve occipital/parietal region. Even if PRES was the leading diagnosis drug levels are not helpful to predict disease. Instead you would stop agent and monitor response.
- Brain biopsy would be highly dangerous given location and unnecessary as next step.
- EBV virus is linked to post-transplant lymphoproliferative disease which can cause CNS changes but the patients clinical pattern and timeline would be atypical.
- The brain lesions are also atypical for toxo. In addition serology would be difficult to interpret particularly in immune-suppressed patient and CSF PCR preferred if toxo was truly suspected.
Other resources
https://pubmed.ncbi.nlm.nih.gov/31567413/
Author Jeremey Walker from UAB
This question was uploaded on 4/13/22