EBV positive inflammatory follicular dendritic cell sarcoma of colon with clonal immunoglobulin receptor gene rearrangement: a case report and literature review

Background: Epstein-Barr virus positive (EBV+) inflammatory follicular dendritic cell (FDC) sarcoma is a neoplasm of spindled follicular dendritic cells with abundant lymphoplasmacyte infiltration and a consistent association with EBV. It usually involves the liver and spleen but rarely the digestive tract. Herein, we reported a special case of EBV+ inflammatory FDC sarcoma in colon with clonal immunoglobulin (IG) receptor gene rearrangement. Case presentation: A 70-year-old man presented with abdominal distension for 1 month. A pedunculated polyp in ascending colon was revealed by colonoscopic examination. The patient then underwent endoscopic polypectomy. The colonic polyp had extremely prominent lymphoplasmacytic infiltrates with dispersed EBV+ neoplastic cells, highlighted by EBV-encoded small RNA in situ hybridization. The neoplastic cells were immunoreactive for FDC markers (CD21, CD35 and CD23). The tumor also showed an amplification of immunoglobulin heavy chain (IGH) gene rearrangement. Finally, its diagnose was EBV+ inflammatory follicular dendritic cell sarcoma. Conclusions: : We represented a rare case of EBV+ inflammatory FDC sarcoma presenting as a colonic polyp with clonal IGH gene rearrangement. The molecular change is first described in this tumor of colon. Awareness of this rare neoplasm in gastrointestinal tract is important for accurate diagnosis and well patient management.