Dermatofibromas are hard brown or red lumps under the skin. They usually develop on exposed areas of skin, such as the legs, arms, and back. Dermatofibromas do not develop into cancer. In general ...

They typically feel firm and hard. If your tumor is benign, it won’t require treatment, but if it is malignant, it will need to be surgically moved. Finding a lump under your skin can be ...