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.