Livedo vasculopathy vs small vessel cutaneous vasculitis: cytokine and platelet P-selectin studies.

OBJECTIVE: To assess the role of platelets and lymphocyte-related immunological mechanisms in livedo vasculopathy (LV) and cutaneous small vessel vasculitis (CSVV). Livedo vasculopathy is thought to be related to the thrombotic occlusion of small and medium-sized dermal vessels. Cutaneous small vessel vasculitis comprises a heterogeneous group of disorders in which the main pathogenetic events could be modulated by circulating cytokines.

DESIGN: Case series study of 2 groups of patients affected respectively with LV and CSVV.

SETTING: A large clinical and research institute for the study and treatment of cutaneous diseases.

PATIENTS: Consecutive patients with clinically and histologically proved idiopathic LV (n = 8) and CSVV (n = 20) were studied and compared with healthy donors (n = 20). Patients with potentially correlated systemic diseases were excluded.

MAIN OUTCOME MEASURES: Surface expression of platelet P-selectin and circulating level of interleukin (IL) 1beta, tumor necrosis factor alpha (TNF-alpha), IL-8, IL-2, and soluble IL-2 receptor.

RESULTS: The IL-2 and soluble IL-2 receptor levels were significantly higher in serum samples from patients with both LV (1.24 +/- 0.46 IU/mL [mean +/- SD] vs 0.46 +/- 0.24 IU/mL, P<.001; 899 +/- 368 IU/mL vs 628 +/- 132 IU/mL, P<.02) and CSVV (0.91 +/- 0.57 IU/mL, P<.02; 1087 +/- 451 IU/mL, P<.001) than in those from the healthy controls. The serum levels of IL-1beta, TNF-alpha, and IL-8 were higher in patients with CSVV than in controls (7.53 +/- 6.7 pg/mL vs 4.58 +/- 2.72 pg/mL; 23.7 +/- 12.6 pg/mL vs 10.82 +/- 2.46 pg/mL, P<.001; 37.8 +/- 46 pg/mL vs 8.25 +/- 3.53 pg/mL, P<.02, respectively). No significant difference in the serum levels of IL-1beta (7.2 +/- 4.9 pg/mL), TNF-alpha (12.9 +/- 3.47 pg/mL), and IL-8 (5.9 +/- 4.13 pg/mL) was observed in patients with LV compared with controls. An increased expression of platelet P-selectin was also detected in patients with LV in comparison with controls and patients with CSVV. The mean +/- SD percentage of positive cells for P-selectin was 43% +/- 5% in the patients with LV, 5.1% +/- 2% in the controls (P<.001), and 5.3% +/- 2% in the patients with CSVV (P<.001).

CONCLUSIONS: Taken together, these data demonstrate that different pathogenetic mechanisms are operative in LV and CSVV. In fact, platelet and lymphocyte activation is present in LV, whereas the levels of inflammatory mediators are in a normal range. In CSVV, the high serum levels of proinflammatory cytokines suggest that they are actively involved in the pathogenesis of cutaneous vasculitis.