Does scleroderma present as a small round redness on skin right above the ankle and nothing else?

Rarely: There are localized forms of scleroderma although these are rare. A dermatologist should be able to tell you for certain.

Dermatitis: Scleroderma is not a skin disease. It is an auto-immune disease which causes inflammation and scar tissue formation in the connective tissue which is just under the skin. There are many presentations, but it often initially presents with tightness around joints of the hands or feet. See your doctor for diagnosis.