Sneddon syndrome, also known as idiopathic livedo reticularis with cerebrovascular accidents, is an uncommon (and likely underdiagnosed) syndrome that consists of ischemic strokes and generalized livedo racemosa. The etiology is unknown, but some cases have been reported as inherited in an autosomal-dominant fashion.
Sneddon syndrome predominantly occurs in young women, and the first cerebral ischemic event is usually before the age of 45. The key cutaneous feature is a persistent livedo reticularis, often in a livedo racemosa pattern (form of livedo reticularis consisting of a large branching pattern, usually on the trunk, limbs, and proximal extremities).
Many individuals with Sneddon syndrome have antiphospholipid antibodies. The prevalence has been reported to be from 0% to 85%. Regardless of whether patients have antiphospholipid antibodies, individuals with Sneddon syndrome have identical occlusive arteriopathy and endothelial damage. Up to 35% will have antiendothelial cell antibodies.
Clinical features:
Livedo racemosa – often precedes the onset of focal neurologic symptoms.
Headache and vertigo – most frequent symptoms; may precede livedo racemosa by several years, but are nonspecific.
Ischemic strokes – most symptoms are from middle cerebral artery infarcts: hemiparesis, sensory alterations, and aphasia. Less commonly, there may be dysarthria, visual field deficits, or sudden spontaneous falls.
Secondary symptoms and other organ manifestations include arterial hypertension (65%), valvulopathy (61%), ischemic heart disease, ocular symptoms, renal involvement (50% to 70%), gastrointestinal symptoms, recurrent deep vein thrombosis, and fetal loss.
The prognosis is poor. Mortality has been reported to be 9.5% over an observation period of 6.2 years.
Codes
ICD10CM: M30.8 – Other conditions related to polyarteritis nodosa
SNOMEDCT: 238776001 – Sneddon syndrome
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Differential Diagnosis & Pitfalls
Many other causes of persistent livedo reticularis or livedo racemosa are in the differential diagnosis, particularly because cutaneous findings in Sneddon syndrome will often precede neurological symptoms.
Polyarteritis nodosa – Cutaneous variant is more likely to have livedo racemosa and nodules. Histology: leukocytoclastic vasculitis.
Cholesterol emboli – Livedo reticularis in an elderly person with atherosclerotic disease who may have had recent vascular surgery. Characteristic histology shows cholesterol clefts within thrombi.
Necrotizing livedo reticularis – May involve cutaneous nodules and ulcerations. This has many disease associations, including leukocytoclastic vasculitis, calciphylaxis, cryoglobulinemia, granulomatosis with polyangiitis, atrial myxomas, Graves' disease, connective tissue diseases, acute lymphocytic leukemia, and renal cancer.
Amantadine-induced livedo reticularis – Usually occurs on the legs. (Amantadine is used to treat Parkinson's disease and fatigue associated with multiple sclerosis.)
