SMA is expressed by activated fibroblasts and myofibroblasts in various pathological contexts, including foreign body reactions.40 Vimentin is highly expressed in osteosarcoma cells and is also expressed in immune cells, including myeloid cells, and non-malignant mesenchymal cells, and thus served as a positive staining control.41-43 We observed that CD68+ macrophages, SMA+ fibroblasts, and CD8+ T-cells all localized to the peritumoral region in a concentric fashion (Figure 2F). Here, SMN1 is linked to osteosarcoma.