|Classification and external resources|
Livedo reticularis is a common skin finding consisting of a mottled reticulated vascular pattern that appears like a lace-like purplish discoloration of the skin.:1615 The discoloration is caused by swelling of the venules owing to obstruction of capillaries by thrombi. It can be caused by any condition that makes venules swell.
The condition may be normal or may be related to more severe underlying pathology. It has a broad differential diagnosis, broadly divided into possible blood diseases, autoimmune (rheumatologic) diseases, heart (cardiovascular) diseases, cancers, and endocrine disorders. It can usually (in 80% of cases) be diagnosed by biopsy.
It may be aggravated by exposure to cold and occurs most often in the lower extremities.
The condition's name derives from the Latin livere meaning bluish and reticular which refers to the net-like appearance.
A number of conditions may cause the appearance of livedo reticularis:
- Cutis marmorata telangiectatica congenita a rare congenital condition
- Sneddon syndrome - association of Livedoid vasculitis and systemic vascular disorders, such as strokes, due to underlying genetic cause.
- Idiopathic livedo reticularis - the most common form of livedo reticularis and is a completely benign condition of unknown cause affecting mostly young women during the winter. It is a lacy purple appearance of skin in extremities due to sluggish venous blood flow. It may be mild, but ulceration may occur later in the summer.
- Secondary livedo reticularis:
- Vasculitis autoimmune conditions:
- Obstruction of capillaries:
- Cryoglobulinaemia - proteins in the blood that clump together in cold conditions.
- Antiphospholipid syndrome due to small blood clots
- Hypercalcaemia (raised blood calcium levels which may be deposited in the capillaries)
- Haematological disorders of Polycythaemia rubra vera or Thrombocytosis (excessive red cells or platelets)
- Infections (syphilis,tuberculosis, lyme disease)
- Assc with Acute Renal Failure due to cholesterol emboli status post cardiac cath.
- Arteriosclerosis (cholesterol emboli) and homocystinuria (due to Chromosome 21 autosomal recessive Cystathionine beta synthase deficiency)
- Intra-arterial injection (especially in drug addicts)
- Ehlers-Danlos Syndrome—connective tissue disorder, often with many secondary conditions. Livedo Reticularis may be present in all types.
- Beta IFN treatment in i.e. Multiple Sclerosis 
- Pheochromocytoma 
- Livedoid vasculopathy and its association with factor V Leiden mutation 
- FILS syndrome (Polymerase ε1 mutation in a human syndrome with facial dysmorphism, immunodeficiency, livedo, and short stature) 
- Primary hyperoxaluria,Oxalosis(oxalate vasculopathy) 
- CMV infection (Very rare clinical form of CMV infection, presenting with persistent fever and livedo reticularis on the extremities and cutaneous necrotizing vasculitis of the toes) 
- Livedo reticularis associated with rasagiline 
- Generalized livedo reticularis induced by silicone implants for soft tissue augmentation 
- As a rare skin finding in children with Down Syndrome. 
- Idiopathic Livedo reticularis with polyclonal IgM hypergammopathy. 
- CO(2) angiography ( rare, reported case.)
- A less common skin lesion of Churg-Strauss syndrome 
- Erythema nodosum-like cutaneous lesions of sarcoidosis showing livedoid changes in a patient with sarcoidosis and Sjögren's syndrome.
- Livedo vasculopathy associated with IgM anti-phosphatidylserine-prothrombin complex antibody.
- Livedo vasculopathy associated with Plasminogen activator inhibitor-1(PAI-1) promoter homozygosity and prothrombin G20210A heterozygosity 
- As a first sign of metastatic breast carcinoma(very rare) 
- Livedo reticularis associated with renal cell carcinoma.(rare) 
- Methylphenidate and dextroamphetamine-induced peripheral vasculopathy. 
- Buerger's disease (as an initial sypmtom) 
- As a rare manifestation of Graves hyperthyroidism 
- Livedo reticularis associated with pernicious anaemia.
- Moyamoya disease(s a rare, chronic cerebrovascular occlusive disease of unknown etiology. It is characterized by progressive stenosis of the arteries of the circle of Willis leading to an abnormal capillary network and resultant ischemic strokes or cerebral hemorrhages)
- Livedo reticularis associated with the use of a midline catheter.
- Familial primary cryofibrinogenemia. 
Other than identifying and treating any underlying conditions in secondary livedo, idiopathic livedo reticularis itself may improve with warming the legs, but once established the skin discolouration may become permanent.
- Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0.
- "livedo reticularis" at Dorland's Medical Dictionary
- Case 5-2009: A 47-year-old woman with a rash and numbness and pain in the legs, N Engl J Med 2009;360:711-20
- Sneddon I (April 1965). "Cerebro-Vascular Lesions And Livedo Reticularis". Br J Dermatol 77: 180–5. doi:10.1111/j.1365-2133.1965.tb14628.x. PMID 14278790.
- Gibbs M, English J, Zirwas M (2005). "Livedo reticularis: an update". J Am Acad Dermatol 52 (6): 1009–19. doi:10.1016/j.jaad.2004.11.051. PMID 15928620.
- Feldaker M, Hines E, Kierland R (1955). "Livedo reticularis with summer ulcerations". AMA Arch Derm 72 (1): 31–42. PMID 14387292.
- Golden R (March 1963). "Livedo reticularis in systemic lupus erythematosus". Arch Dermatol 87: 299–301. PMID 13948706.
- Sigmund W, Shelley W (1954). "Cutaneous manifestations of acute pancreatitis, with special reference to livedo reticularis". N Engl J Med 251 (21): 851–3. doi:10.1056/NEJM195411182512104. PMID 13214346.
- Langhof H, Braun G, Matzkowski H (1957). "[Livedo reticularis due to cold gelation of the blood by gamma-plasmacytoma.]". Arch Klin Exp Dermatol 205 (4): 343–50. PMID 13522017.
- Kazmier F, Sheps S, Bernatz P, Sayre G (1966). "Livedo reticularis and digital infarcts: a syndrome due to cholesterol emboli arising from atheromatous abdominal aortic aneurysms". Vasc Dis 3 (1): 12–24. PMID 5903590.
- Stewart W, Lauret P, Testart J, Thomine E, Boulliê M, Leroy D (1977). "[Cutaneous cholesterol emboli (author's transl)]". Ann Dermatol Venereol 104 (1): 5–8. PMID 843026.
- Fleischer A, Resnick S (1990). "Livedo reticularis". Dermatol Clin 8 (2): 347–54. PMID 2191805.