Epstein-Barr virus-associated smooth-muscle tumor (EBV-SMT) is an extremely rare neoplasm which occurs in immunocompromised patients, such as those with AIDS, drug-induced immunosuppression post-transplantation or congenital immunodeficiency (e.g. common variable immunodeficiency, ataxia-telangiectasia). EBV-SMT was first reported in the 1990s. The pathogenesis is disputed but it is generally accepted that it begins with EBV infecting normal muscle which then proliferates in the setting of immunosuppression and ultimately undergoes neoplastic transformation. These tumors demonstrate a variable degree of local invasion but a low propensity for metastasis. The central nervous system (CNS) is a common site affected by EBV-SMTs—particularly in AIDS-related cases but they have been reported at multiple sites including lung, liver, bone, kidney, intestines, stomach, genitourinary tract and adrenals. The condition affects both children and adults with a slight female preponderance. We present the case of a previously healthy 8-year-old female who presents with headache and vaginal bleeding. She underwent an uneventful resection of the skull base lesion via an extradural anterior petrosectomy or Kawase’s approach which was determined to be an EBV-SMT. Subsequent evaluation revealed systemic disease burden and a nonspecific CD4+ and CD8+ dysfunction. CT chest, abdomen and pelvis revealed a left adrenal mass and multiple pulmonary nodules. The adrenal mass had avid uptake of FDG. She underwent left adrenalectomy and pathology was identical to that found for the skull base lesion.
EBV-SMTs are very rare and occur primarily as a consequence of HIV/AIDS or drug-induced immunodeficiency in the setting of organ transplantation. These tumors have also been reported in patients with congenital immunodeficiency but this presentation is extremely rare and a Medline search for “EBV AND smooth muscle tumor” revealed only 5 cases. All other reported cases were associated with HIV/AIDS and/or immunosuppression in the aftermath of organ transplantation. Thus, while the clinical suspicion of a congenital or acquired immunodeficiency was low, the finding of an EBV-SMT compels the clinician to perform a thorough evaluation of immune competence. As these patients are at risk for subsequent infections and other malignancies, knowledge of their immune status should be incorporated into their general care and at the very least, lead to increased surveillance.
The precise pathogenic mechanism of EBV-SMT in immunocompromised individuals remains unclear. In vitro evidence suggests that small vessels possess the obligate EBV CD21 receptor required for B cell infection by the virus. EBV is ubiquitous in most human populations and in the setting of acquired immunodeficiencies, it is thought that a dormant virus becomes reactivated following reprieve from the host immunologic check. In the current case, viral serologies suggested a recent EBV infection. This finding suggests rapid progression from infection to tumorigenesis in these patients.