Livedo reticularis is a lace-like, bluish-purple mottling of the skin caused by changes in blood flow through small vessels near the surface. It looks like a net or web pattern, most commonly appearing on the legs but sometimes on the arms or trunk. In many cases it’s completely harmless, triggered by cold temperatures and disappearing when you warm up. In other cases, the pattern signals an underlying condition that needs attention.
What Causes the Pattern
Your skin is supplied by tiny arteries that branch outward in cone-shaped zones. Where those zones meet at their edges, blood flow is naturally slower and oxygen levels are lower. When something causes the small blood vessels in those border zones to constrict or the blood flowing through them to slow down, the deoxygenated blood shows through the skin as a purple or blue network. The centers of each “ring” in the pattern correspond to where blood flow is still adequate, which is why they look relatively normal while the edges turn blue.
Cold is the most common trigger. When your body temperature drops, surface blood vessels tighten to conserve heat, and the areas with the weakest circulation turn color first. But cold isn’t the only cause. Anything that reduces flow through those small vessels, whether it’s a blood-thickening condition, inflammation in the vessel walls, or a physical obstruction, can produce the same net-like appearance.
The Harmless Version: Cutis Marmorata
The most common form of livedo reticularis is called cutis marmorata, and it’s a normal physiological response to cold. It appears most often in young women, typically on the legs, and fades slowly once you warm up. No treatment is needed.
Babies and young children are especially prone to this mottling because their bodies aren’t as efficient at regulating temperature yet. In infants, the bluish pattern on the trunk and limbs after cold exposure is expected and usually resolves with warming. Most babies outgrow the tendency by about one month of age, though it can linger for several months without being a concern. If the mottling doesn’t go away with warming or persists past six months, it may point to an underlying issue such as a thyroid problem or a vascular abnormality that warrants further evaluation.
When It’s Not Just the Cold
If livedo reticularis shows up regardless of temperature, doesn’t fade with warming, or is accompanied by other symptoms, it falls into a different category. This “pathologic” form can be divided into several groups based on what’s disrupting blood flow.
- Vasospasm from connective tissue disease. The most common cause of pathologic livedo reticularis is spasm of small blood vessels associated with autoimmune connective tissue disorders. People with Raynaud phenomenon, where fingers turn white and blue in the cold, frequently develop livedo reticularis as well.
- Thickened or abnormal blood. Conditions that make the blood thicker or alter its components, such as polycythemia vera (too many red blood cells) or certain blood cancers that produce abnormal proteins, can slow circulation enough to create the pattern.
- Vessel wall inflammation. Vasculitis, or inflammation of blood vessel walls, changes how blood flows through the skin. When livedo reticularis appears alongside skin ulcers or painful nodules, vasculitis becomes a leading suspect.
- Blood clots and antiphospholipid syndrome. Conditions that make blood clot too easily can block the tiny arteries feeding the skin. Antiphospholipid syndrome, an autoimmune disorder that promotes abnormal clotting, is one of the better-known associations.
- Medications. Certain drugs can trigger the pattern by affecting blood vessel tone or clotting.
Livedo Reticularis vs. Livedo Racemosa
Doctors distinguish between two related patterns. Classic livedo reticularis forms complete, regular rings in a fine, symmetric net, usually on the legs. Livedo racemosa, by contrast, produces larger, irregular, broken rings that tend to appear on the trunk and upper limbs as well. The distinction matters because livedo racemosa is more strongly linked to serious systemic disease. It’s the pattern most commonly associated with Sneddon syndrome, a condition involving recurrent strokes and widespread livedo in younger adults.
If you’re looking at your own skin and wondering which pattern you have, the key differences are symmetry and completeness. Small, even, closed circles that come and go are more reassuring. Large, irregular, open-ended streaks that persist are worth having evaluated.
How It’s Evaluated
For the cold-triggered version that resolves with warming, no workup is needed. It’s a normal response. But when the pattern is persistent, widespread, or accompanied by other symptoms like joint pain, skin ulcers, numbness, or unexplained blood clots, doctors look deeper.
The evaluation typically focuses on identifying what’s disrupting blood flow. That means blood tests checking for clotting abnormalities, immune markers associated with autoimmune disease, and signs of inflammation. A skin biopsy can sometimes help, particularly when vasculitis or vessel obstruction is suspected, because the changes occur in the small arteries beneath the skin’s surface.
The goal isn’t to diagnose “livedo reticularis” itself. The skin pattern is visible and obvious. The real diagnostic question is whether something systemic is driving it.
Treatment Depends on the Cause
Physiologic livedo reticularis needs no treatment beyond staying warm. Keeping your legs covered in cold weather, wearing warm layers, and avoiding prolonged cold exposure will minimize the appearance.
When an underlying condition is responsible, treatment targets that condition rather than the skin pattern itself. For autoimmune-driven forms, this might involve medications that calm the immune system. For clotting-related causes, blood thinners or antiplatelet therapies are the cornerstone. If vasculitis is involved, controlling the inflammation is the priority.
In cases where the skin changes lead to ulcers, wound care becomes an important part of management. Keeping the affected limb elevated, using compression stockings, and maintaining a moist wound environment all help healing. Pain control matters too, since ulcers associated with these vascular conditions can be significantly painful.
Heat-Induced Livedo: A Separate Condition
There’s a related but distinct pattern caused by repeated heat exposure rather than cold. If you regularly rest a laptop on your legs, sit too close to a space heater, or use a heating pad in the same spot, you can develop a livedo-like mottling in that area. Initially it looks similar to cold-triggered livedo and fades when the heat source is removed. Over time, though, continued exposure causes the pattern to become permanently fixed as a brownish, net-like discoloration. The fix is straightforward: remove the heat source. The temporary version resolves, but the pigmented version may take months to fade or can become permanent.