Epstein-Barr virus-associated smooth muscle tumor presenting as a vulvar mass in an acquired immunodeficiency syndrome patient: a case report.

Smooth muscle tumors in immunocompromised patients have a strong association with Epstein-Barr virus (EBV) infection. EBV-associated smooth muscle tumors (EBV-SMT) are considered as a distinct group of smooth muscle tumors with different clinicopathologic features from conventional smooth muscle tumors. A 31-year-old female patient presented with a 2-cm mass at the left labium majus, the clinical diagnosis of which was a Bartholin lesion. She had acquired immunodeficiency syndrome diagnosed 29 months before. Excisional biopsy revealed a cellular tumor composed of round- to spindle-shaped cells with mild to moderate nuclear atypia. The tumor cells were immunoreactive for smooth muscle actin and muscle actin (HHF-35). Evidence of EBV infection was confirmed by in situ hybridization for EBV-encoded small RNA-1. To our knowledge, this is the first case of EBV-SMT presenting as a vulvar mass. EBV-SMT should be included in the differential diagnoses of mesenchymal tumor in patients with immunosuppression and in the differential diagnoses of smooth muscle tumor in uncommon sites, including the vulva.