CR2 and leiomyosarcoma: Up to now, there are <100 cases of follicular dendritic cell tumors which have been reported in English literature.[12,25] The differential diagnosis include: sarcoma, Hodgkin disease, leiomyosarcoma, gastro-intestinal stromal tumor (GIST), and inflammatory pseudo-tumor.[8,26,27] According to IHC analyses, FDC sarcoma shows spindle tumor cells arranging in fascicular or storiform patterns, which are immuno-reactive for one or more FDC markers: CD21 (C3d receptor, positive in 93% of cases) and CD35 (C3b receptor, positive in 89% of cases).