Patients with venous disease often have darkened skin changes to their lower legs and ankles. Prolonged venous disease or reflux may advance to venous hypertension (high pressure in the veins) and vein dilatation. With this high pressure there occurs a passage of red blood cells through the thin layer of cells that line the cell wall. Eventually this results in the breakdown and conversion of hemoglobin to a yellowish brown granular pigment (hemosiderin) formed by breakdown of hemoglobin.
The hemosiderin remains as a brown pigment stain on the skin. It is typically located on the lower inside third of the lower leg but skin changes can involve the entire gaiter area (the area on the inside of the ankle to the inside of the mid-calf) distribution. With time, the skin changes or pigmentation begin to darken and may eventually appear dark brown or almost black. The advancement of venous disease to chronic venous disease and skin ulceration can be prevented. Like most medical condition early evaluation and detection is important.