Livedo reticularis is a blue-reddish skin discoloration and most often localized in the lower extremities. The pathological mechanism of this is poorly understood. Probably it is related to the peripheral blood flow redistribution. Livedo reticularis mostly represents an idiopathic condition but may be associated with systemic diseases.
Livedo reticularis is a disorder in which blood vessels are constricted, or narrowed. It results in mottled discoloring on large areas of the legs or arms. Livedo reticularis refers to a condition in which dilation of capillary blood vessels and stagnation of blood within these vessels causes mottled discolouration of the skin. It is described as being reticular (net-like) cyanotic (reddish blue discolouration) cutaneous discolouration surrounding pale central areas.
It occurs mostly on the legs, arms and trunk and is more pronounced in cold weather. The mottled look seen in a person with livedo reticularis occurs when some of the blood vessels feeding the skin go into spasm. Symptoms of livedo reticularis include a mottled, or lace-like, appearance of reddish blue areas on the skin. The mottling is more apparent on the thighs and forearms, and sometimes the lower abdomen. The appearance is due to altered flow in small blood vessels feeding the upper skin so that other vessels dilate to compensate. This can arise for a variety of reasons.
Cutis marmorata causes temporary livedo in about 50% of normal infants and many adults when exposed to the cold and is a physiological response to cold. It is more intense and persistent in conditions associated with debility and other factors that cause stasis within blood vessels. The mottling is diffuse, temporary, mild and usually symptomless. Cutis marmorata telangiectatica congenita is a rare condition in which the livedo is present at birth or soon after. There may be other congenital abnormalities including neurological and intellectual problems, and it can be familial. The livedo is usually severe but may improve with age.
Idiopathic livedo reticularis (i.e. cause unknown) occurs most commonly in young and middle-aged females, particularly during winter. Mottling occurs first only on exposure to cold but can become permanent. Tingling and numbness on cold exposure are common. Sometimes swelling, and rarely ulcers may develop in winter. In another less common variant, swelling of the feet and ankles and ulceration occurs in the spring and summer months. Sneddon's syndrome is a form of idiopathic livedo reticularis with systemic involvement i.e. internal blood vessels are affected, most commonly in the brain, eye and heart.
There is no treatment for livedo reticularis. Rewarming the area in idiopathic cases or treatment of the underlying cause of secondary livedo may reverse the discolouration. However, over time the vessels become permanently dilated and livedo reticularis becomes permanent regardless of the surrounding temperature.