An unusual cause of a multifocal bone lesion: Epstein–Barr Virus-Associated Smooth Muscle Tumour (EBV-SMT) involving bone

Abstract

Epstein–Barr virus-associated smooth muscle tumours (EBV-SMTs) are rare neoplasms of uncertain biological potential, which occur in the setting of immunodeficiency of a variety of causes, including HIV infection and post-transplant immunosuppression. The association between SMTs and immunosuppression was first described by Pritzker et al. in 1970. They have a male predominance and occur at unusual sites in adults. The CNS is the most common site in the setting of HIV while post transplantation cases are more likely to occur in liver, lungs and GIT. Other sites have also been reported including bone. We report a case of an EBV-SMT presenting as multifocal, lucent lesions of proximal tibia, proximal fibula and distal femur in a 45-year-old female patient with previous lung transplantation. A biopsy of the tibial lesion showed a smooth muscle tumour with positive staining for EBER (EBV ISH) supporting a diagnosis of EBV-SMT. EBV-SMTs of bone are rare and to our knowledge this is the first example of multifocal EBV-SMT confined to bone.