A Case of Retroperitoneal Follicular Dendritic Cell Sarcoma

We present a case of retroperitoneal follicular dendritic cell sarcoma. Abdominal ultrasound revealed retroperitoneal tumor in a 72-year-old woman. Contrast-enhanced computed tomography (CT) showed a well-demarcated mass in the retroperitoneal space, necessitating surgery for suspected retroperitoneal soft-tissue malignancy. The resected specimen was immunohistochemically confirmed to be of follicular dendritic cell origin. Extracapsular invasion and lymph node metastasis were also seen, with the resected tumor proving histopathologically to be follicular dendritic cell sarcoma (FDCS). FDCS is a rare malignant tumor originating in lymphoid tissue. FDCS is definitively diagnosed by immunohistochemical examination using specific markers.