There are two kinds of scleroderma: Localized. The skin and soft tissue structures directly underneath it are affected, most often in children or young adults. It often starts as small patches of hard skin (morphea) over the trunk but can start over the arms or legs. There may be one patch, a few patches, or a large number of patches that may conglomerate together and extend over large areas of the skin. Sometimes a single limb — such as an arm or leg — may be affected (linear scleroderma) or hardening of the skin may indent the soft tissue underneath the forehead (en coup de sabre). Internal organ involvement is typically uncommon. Systemic. Internal organs are nearly always affected in addition to the skin. This more serious type of scleroderma can be disfiguring if skin thickening extends to the face. It can damage the blood vessels and impact the heart, lungs and kidneys. Based on the extent of skin involvement, it can be limited (skin thickening below knees and elbows) or diffuse (skin thickening extending to upper arms, thighs and trunk). Women between ages 30 and 60 are most commonly affected. Having a family history of autoimmune conditions also is a risk factor.