Introduction
Epstein-Barr virus associated smooth muscle tumors (EBV SMT) are rare
neoplasms that occur in immunocompromised individuals including
recipients of solid organ transplant (SOT), patients with human
immunodeficiency virus and other primary
immunodeficiencies1-3.
Unlike in EBV-driven lymphomas where CD21 permits B-cell entry, multiple
reports have shown that SOT EBV-SMTs frequently lack this receptor.
Thus, the tumorigenesis of EBV-SMT remains an ongoing area of
importance, as further characterizing the mechanisms responsible for
cell invasion will help direct novel
treatments1,4,5.
In the pediatric SOT setting, EBV-SMTs typically present shortly after
transplant and can affect multiple sites, frequently including
hepatobiliary and respiratory
systems1-3. Multifocal
lesions present in the majority of patients at diagnosis and likely
represent primary tumors from multiple infectious events rather than
metastasis from a single primary
site1,2,6.
The presence of multiple tumors in an immunocompromised host occurring
in non-hollow visceral organs known to have limited smooth muscle i.e.
liver, lung, dura, spleen, and bone should raise high suspicion for EBV
SMT2,6,7.
The overall incidence of EBV SMT in immunocompromised patients is
estimated to be 1-5% with approximately 30 pediatric cases of EBV-SMT
in post-solid organ transplant recipients having been
reported1,3,6,8,9.
An institutional review of greater than 5,000 SOT patients showed the
incidence of EBV SMT disproportionality affects
children8. With a
paucity of knowledge about these rare tumors, we investigated the
occurrence of EBV SMT in our pediatric heart transplantation population
from 1985-2017. Of the 152 patients evaluated, three cases of EBV-SMTs
were identified. We aim to highlight the similarities and differences
found in our cohort and compare that to what has been previously
reported in the literature. Further, we attempt to realize potential
risk factors for the development of EBV-SMT in the pediatric population
and discuss the role of current therapies.