In 1965, Sneddon told of his experience with 6 patients all of whom had presented themselves with what he called "cerebro-vascular lesions and livedo reticularis." [4] His patients had neurologic signs and symptoms associated with a widespread branched pattern of livedo, which correctly should have been termed livedo racemosa, not livedo reticularis (see also livedo racemosa) (Fig. 5). None of the patients presented with ulceration of the skin in zones of livedo racemosa. A similar combination of signs and symptoms had already been told of by Champion and Rook, in 1960. [3] Sneddon as well as Champion and Rook, suggested that the condition may be the result of an arteriolitis, even though they noted similarities of features clinical to periarteritis nodosa. Zelger et al., in 1992, demonstrated that small to medium-sized arteries situated at the dermis-subcutis border are involved in Sneddon syndrome, and not arterioles or venules. [22] The same authors acknowledged, in 1993, [23] that in the same patient, features of Sneddon syndrome and livedo vasculitis may appear together, even though they were convinced that livedo vasculitis affected venules mostly and was not regarded by them to be a vasculitis. Whether or not there is a relationship of Sneddon syndrome to livedo vasculitis is not yet understood, but it is well known that both conditions may be accompanied by livedo racemosa, and both conditions have been encountered in patients with lupus erythematosus. The relationship between Sneddon syndrome and periarteritis nodosa is equally opaque. It has been suggested that Sneddon syndrome may be caused by a variety of factors such as coagulopathies, atherosclerosis, or embolization, e.g., in an arterial myxoma. [24] In sum, in the contemporary literature of dermatology and dermatopathology, the term Sneddon syndrome is used as a description clinical for the presence together of livedo racemosa with neurologic signs and symptoms. Whether the "syndrome" represents a distinctive disease entity or rather a pattern produced by a variety of etiologic agents, is not yet understood.