Livedo reticularis. Signs in the skin of disturbance of blood viscosity and of blood flow.

The clinical sign of livedo reticularis derives from stasis of blood in the superficial venous drainage systems of the skin. Many factors can delay the flow of de-oxygenated blood away from the skin, notably hyperviscosity of the blood itself and obstruction due to disease affecting dermal arteries, capillaries, or venules.