Using gene array-based expression profiling of fresh frozen specimens of fibroblastic tumors (desmoid type fibromatosis-DTF and solitary fibrous tumor-SFT) and macrophage-rich tumors (tenosynovial giant cell tumor-TGCT/CSF1), we previously discovered novel types of stromal reaction patterns that emphasize the variations in the fibroblast and macrophage compartment in breast cancer between different patients [1,2,8,9]. The gene discussed is CSF1; the disease is breast cancer.