The Purple Digit: An Algorithmic Approach to Diagnosis

Patrick J. Brown; Matthew J. Zirwas; Joseph C. English III


Am J Clin Dermatol. 2010;11(2):103-116. 

In This Article

2. Cold-induced and Cold-associated Conditions

The first consideration when dealing with cold-related changes in the digits is differentiating a pathologic response from a normal reaction to cold weather. Pathologic responses can be either idiopathic (primary) or secondary. Similarities in pathophysiology and clinical findings amongst the various acral vascular syndromes have led some to suggest the term 'neurovascular instability syndrome' be used as a broad term to classify all aberrant neurovascular responses to environmental stimuli.[15] Nevertheless, a detailed history of cold exposure and cutaneous response can aid in distinguishing between acral vascular syndromes.

2.1 Vasospastic Disorders

Raynaud phenomenon is classically described as digital artery vasospasm producing white (ischemic), then blue/purple (cyanotic), followed by red (reperfusion) changes in the fingers.[16] Primary Raynaud phenomenon, referred to as the idiopathic or uncomplicated type, is suggested when cold or emotional stress precipitate episodes of non-ulcerating, symmetric ischemia that occur in otherwise healthy patients with normal erythrocyte sedimentation rates, nail-fold capillaries, and negative antinuclear antibodies.[17] Patients with primary Raynaud should be followed, as longitudinal studies have shown an increased risk of developing connective tissue disease.[18,19] A detailed history will help to diagnose Raynaud, especially when overlap with other acral vascular syndromes such as erythromelalgia exists.[20] Also, cold- or traumainduced reflex sympathetic dystrophy may produce Raynaud-like changes in the digits associated with intense allodynia and joint pain.[21,22] Of particular interest to the dermatologist is the intralesional injection of bleomycin in acral areas for the treatment of recalcitrant warts, which may cause either transient or persistent Raynaud phenomenon.[23,24] Complete algorithms for the diagnosis of secondary Raynaud phenomenon have been published elsewhere.[25] Raynaud phenomenon occurs frequently in patients with rheumatologic diseases including scleroderma (>90%), systemic lupus erythematosus (10–45%), Sjögren syndrome (33%), dermatomyositis (20%), and rheumatoid arthritis (10–20%); therefore, these conditions warrant consideration in the work-up of secondary Raynaud phenomenon.[26] A recent meta-analysis showed that no evidence exists to support the use of oral vasodilator drugs other than calcium channel blockers in the treatment of primary Raynaud phenomenon.[27]

Unlike Raynaud phenomenon, patients with acrocyanosis do not experience a return to baseline circulation between vasospastic episodes. Although cold may exacerbate cyanosis, rewarming does not return circulation to baseline. The primary form is more likely to occur in female patients under the age of 30 years[28] (figure 2). Acrocyanosis may also be secondary to a number of conditions (table II). In a study of 68 patients with malignancy and paraneoplastic disorders affecting the acral vasculature, 24% manifested acrocyanosis.[36] Acrocyanosis has been reported as a presenting symptom for Hodgkin lymphoma[46] and ovarian cancer.[47] Acrocyanosis secondary to inherited metabolic disorders is more likely to present in childhood, but there is one case of a heterozygote with Fabry disease presenting at 47 years of age.[48] Acrocyanosis is present in one-third of patients with antiphospholipid antibodies and may be seen in conjunction with other cutaneous manifestations of antiphospholipid antibody syndrome such as dermatographism, urticaria, diffuse alopecia, livedo reticularis, cutaneous nodules, ulceration, and purpura.[31] The purpuric changes from this syndrome can also cause purple digits. Although published reports are lacking, the authors have noted several cases of acrocyanosis in intensive care patients maintained on vasopressors. In the case of mental retardation and schizophrenia, acrocyanosis is postulated to arise from immobility,[39] but causality has not been firmly established. Finally, acrocyanosis occurs as part of the 'puffy hand syndrome,' an entity unique to intravenous drug abusers who inject their hands or fingers.[43,49] Primary treatment of any acrocyanosis involves avoidance of cold exposure, which can exacerbate vasospasm. Unlike Raynaud phenomenon, calcium channel blockers have not been found to be effective in the treatment of acrocyanosis.[11]

Figure 2.

Primary acrocyanosis.


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