Ever since Raynaud described the discoloration of hands and fingers in response to cold stimuli, the nomenclature of this phenomenon has progressively evolved [1]. Various terms have been used to describe these cold- and stress-induced events including Raynaud’s phenomenon, Raynaud’s disease, and Raynaud’s syndrome. It is recognized that RP may be the manifestation of several different underlying pathologies and that it can be associated with a heterogeneous group of clinical disorders. Therefore, the dilemma has always been finding the precise definition of RP. Maurice Raynaud by his careful clinical observations recognized the great variety of acral circulatory disorders characterizing the phenomenon. In his preface, Raynaud writes that it is easier to describe a new disease than to bring the great variety with which the phenomenon manifests itself under a common denominator. This prompted him to propose four criteria to identify RP: (1) discrete episodes of change in color, of the vasospastic type, induced by cold exposure or emotional stress; (2) bilaterality; (3) normal pulsations in palpable stress; and (4) absence of gangrene, or only minimal grades of cutaneous gangrene. A patient having vasospastic events meeting these criteria was originally said to have “Raynaud’s disease.” The nomenclature changed when in 1901 Hutchinson [4] described RP as a “phenomenon” that was either due to an underlying disease, such as an obstruction in the arterial system, or exists without such an obstruction. Thus the astute observations of Raynaud and Hutchinson indicated that RP was linked to a variety of disorders that involved the acral circulation.

In 1932, these observations prompted Allen and Brown [5] to propose a nomenclature and definition for uncomplicated or “primary” RP (Box 2.2). They reviewed and modified Raynaud’s original description and proposed the following criteria: (1) vasospastic attacks induced by cold exposure; (2) bilateral involvement of the extremities; (3) absence of gangrene or involvement of only the skin of the fingertips; and (4) a history of symptoms for at least 2 years, with no evidence of an underlying disease. Since that time, a digital phenomenon that met these criteria and showed a cutaneous discoloration from white to bluish to red was called primary RP instead of Raynaud’s disease. These criteria allowed the practitioner to distinguish primary RP from other conditions associated with tissue necrosis or from vascular disease of hands and fingers with asphyxia due to local anatomic arterial obstructions. Since then RP in the presence of an underlying disease is labeled “secondary Raynaud’s phenomenon” (see Table 2.1).