EBV-associated smooth muscle tumor

Epstein-Barr virus-associated smooth muscle tumours (EBV-SMT) areare rare and encountered in immunocompromised individuals.

Epidemiology

These tumours are generally exceedingly rare, and only seen with any frequency in the setting of immunosuppression, particularly in HIV/AIDS patients, but also post-transplantation and in common variable immunodeficiency syndrome. In the HIV population, they are encountered as non-AIDS-defining cancers in both adult and paediatric populations ¹. The age range is therefore defined by the underlying cause of immunosuppression, but they tend to be encountered in young adults (mean age of diagnosis 25 years; range: 2.7 to 49 years) ¹. No strong gender predilection has been identified ¹.

Clinical presentation

Although they occur almost anywhere in the body, the central nervous system (both intra- and extra-axial) is the most common site of involvement, with the gastrointestinal tract, liver, skin, lungs, pharynx, and larynx also relatively frequently involved ^1,2.

Clinical presentation will, therefore, vary widely, depending on tumour location ¹. On occasion, these tumours will be multifocal, representing simultaneous multiple primaries rather than metastases ^1-3.

Pathology

EBV-SMT range from indolent leiomyomas to aggressive leiomyosarcomas ¹. In both cases, co-infection with Ebstein-Barr virus is necessary for the diagnosis ¹. 

Radiographic features

Imaging findings are non-specific, with tumours appearing as enhancing soft-tissue masses ¹.

Treatment and prognosis

Treatment of EBV-SMT is primarily with resection, although radiotherapy and chemotherapy have also been used. In the setting of HIV/AIDS, highly active antiretroviral therapy (HAART) is also potentially indicated ¹.

Prognosis and aggressiveness are variable but seem to be somewhat more favourable than conventional 'sporadic' leiomyosarcomas ¹.