BACKGROUND
Cytomegalovirus virus (CMV) infection predominantly affects
immunocompromised individuals.1 CMV infection can lead
to CMV disease and has been associated with non-relapse mortality
following allogeneic hematopoietic stem cell
transplant.2 CMV disease post allogeneic transplant
commonly affects the lungs or gastrointestinal
tract.1,2 CMV retinitis remains an uncommon
presentation post allogeneic transplant and can be
vision-threatening.3-6 Implementation of prophylaxis
and preemptive strategies have reduced the incidence of CMV disease to
10% in the first year post allogeneic transplant.2,7Our case demonstrates the occurrence of polymerase chain reaction (PCR)
proven mixed viral retinitis (CMV and varicella zoster virus VZV) post
allogeneic stem cell transplant despite multiple prophylactic antiviral
therapies, and features CMV retinitis in the absence of CMV DNAemia.
This case also highlights the emerging challenge of late CMV disease
occurring during secondary prophylaxis with Letermovir. To our knowledge
this represents the first reported case of polyviral retinitis in this
clinical context.