myofibroblastoma. (a) Most of the tumor is formed of hyalinized collagen bundles surrounded by spindle cells, H&E × 400. (b) Cellular area formed of palissading spindle cells, H&E × 400. (c) Staining of spindle and oval cells is more pronounced in the lower right part, CD34 IHC, DAB, Hx × 400. (d) Focal area of spindle and oval cells positive for SMA, IHC, DAB, Hx ×400. See additional files 5, 6, 7, 8 for higher resolution images.