Supplementary Material for: Epstein-Barr virus-positive inflammatory follicular dendritic cell sarcoma occurring in spleen of a patient after chemotherapy for lung carcinoma: a case report

Introduction: Epstein-Barr virus (EBV)-positive inflammatory follicular dendritic cell sarcoma (EBV+ inflammatory FDCS) is a rare neoplasm which occurs almost exclusively in the spleen and liver. Although EBV+ inflammatory FDCS is recognized to show indolent behavior, its pathophysiology including the pathogenesis remains unclear. Case Presentation: We present an EBV+ inflammatory FDCS which occurred in the spleen of a patient under the follow-up for chemotherapy against lung carcinoma. Sequential CT examinations reveal that a splenic lesion was first detectable 5 years after chemotherapy and has grown for another 3 years to form a mass of 4 cm in diameter. Splenectomy was performed. Histologically, a well circumscribed lesion in the spleen exhibited the significant infiltration of lymphocytes and plasma cells in the background of hyalinized fibrous tissue, and large oval-shaped cells were intermingled with lymphocytes and plasma cells. Large oval-shaped cells were found to express CD21 and CD23, and they were shown to be positive for EBV-encoded small RNA (EBER) in situ hybridization. Based on these findings, the splenic lesion was diagnosed as EBV+ inflammatory FDCS. Conclusion: The present case might provide information to discuss the possible pathogenesis of EBV+ inflammatory FDCS in the context with immunosuppression.