Myxofibrosarcoma is a malignant tumor with distinctive histologic features and is believed to be derived from fibroblasts. The function of infiltrating myeloid cells in myxofibrosarcoma is poorly understood. It previously has been shown that a combination of dendritic morphologic features and expression of the C-type lectin, dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN), is useful for identifying DC populations in tissue sections. In the present study, we found that 3% to 61% (median, 22%) of cells in myxofibrosarcomas express DC-SIGN and have dendritic morphologic features. These DC-SIGN--positive cells are not in cell cycle and are consistent with infiltrating DCs. The percentage of DCs in myxofibrosarcomas is independent of tumor grade. It previously has been shown that DC-SIGN--positive cells are either immature DCs or DCs that predominantly activate TH2 cells, both subsets likely to give rise to ineffective antitumor responses. The DC-SIGN--positive DCs that we have identified in myxofibrosarcoma may, therefore, be involved in the induction of ineffective immune responses or even tolerance to tumor antigens.