Follicular dendritic cell sarcoma of lymph node--a rare entity.

Follicular dendritic cells (FDC) are non-lymphoid, non-phagocytic accessory cells in the immune system that are essential for antigen presentation and germinal center reaction regulation. These cells are CD21+, CD35+, CD1a- and S100 protein +/- and they show desmosomes ultrastructurally. The most commonly involved sites by FDC tumors are lymph nodes but may arise at a variety of extranodal sites including oral cavity, tonsil, gastrointestinal tract and liver. Most studies represent single case reports or case series. Our patient presented with tumor in the lymph nodes. Histology revealed tumor cells with abundant eosinophilic cytoplasm, hyperchromatic and pleomorphic nuclei, and prominent nucleoli. The tumor cells were found to be positive for CD21 which is a specific marker for follicular dendritic cells.