[Desmoplastic fibroblastoma].

We report a light microscopic and ultrastructural appearance, and immunohistochemical profile of two benign tumours of soft tissue recently designated as desmoplastic fibroblastoma (collagenous fibroma). The tumours were located in the foot and well demarcated. Microscopically, they were composed of stellate--or spindle--shaped cells embedded in a hypovascular fibrous of fibromyxoid stroma. Immunohistochemical examination showed that tumours were diffusely positive for vimentin and focaly positive for smooth muscle actin and muscle specific actin. Ultrastructurally, the neoplastic cells had features of fibroblasts and myofibroblasts.