Livedo reticularis is a vasospastic disorder of unknown cause that results in a painless, mottled discoloration on large areas of the extremities, generally in a fishnet pattern with reticulated cyanotic areas surrounding a paler central core. It occurs in men and women of all ages. In most instances, livedo reticularis is entirely benign; infrequently, it is associated with an occult malignancy, polyarteritis nodosa, atherosclerotic microemboli, or antiphospholipid antibody syndrome. The disorder is characterized by arteriolar vasoconstriction with capillary and venous dilation; the particular pattern is believed to represent arborization of capillaries surrounding the feeding arteriole.

Livedo reticularis is most apparent on the thighs but can occur on the forearms or lower abdomen and is most pronounced in cold weather. In warm environments, the reticular pattern may fade but does not entirely disappear. A few patients report paresthesias, coldness, or numbness in the involved areas.

Peripheral pulses are normal. The affected regions may be cool. Skin ulceration is rare. Treatment consists of protection from exposure to cold; use of vasodilators is seldom indicated. In the rare patient who develops ulcerations or gangrene, an underlying systemic disease should be excluded.