DISCUSSION:
We report a rare case of polyviral retinitis in a post-allogeneic stem
cell transplant patient, with PCR of the aqueous fluid demonstrating two
viral populations, CMV and VZV, which occurred despite ongoing
prophylaxis for these two viruses, and despite completing two courses of
treatment for CMV viremia, with a documented negative CMV PCR in the
blood prior to the presentation with retinitis. CMV sensitivity testing
performed indicated sensitivity to both agents used for previous
treatment (Ganciclovir and Foscarnet)8. As the CMV
serum PCR was undetectable at the time of the presentation with CMV
retinitis, it is unlikely that this presentation was driven by
resistance to treatment. Presentation of CMV retinitis was likely
multifactorial driven by early CMV reactivation, low CD4 counts and
delayed CD4 lymphocyte recovery in the first 100 days post-transplant
which are all associated with late CMV disease. Other potential
contributing factors are poor CNS and poor retinal penetration of
Letermovir. With very little existing literature on either mixed viral
retinitis or CMV retinitis during Letermovir
prophylaxis9, this case serves to expand the
literature on both topics. The case also highlights the need to expand
efficacy data on secondary prophylaxis with Letermovir to address an
unmet therapeutic need. To our knowledge this represents the first
documented case of mixed viral retinitis in this therapeutic context.