LIVEDO VASCULOPATHY VS SMALL VESSEL CUTANEOUS VASCULITIS - CYTOKINE AND PLATELET P-SELECTION STUDIES

Objective: To assess the role of platelets and lymphocyte-related immu nological mechanisms in livedo vasculopathy (LV) and cutaneous small v essel 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 d isorders in which the main pathogenetic events could be modulated by c irculating 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 pro ved idiopathic LV (n = 8) and CSVV (n = 20) were studied and compared with healthy donors (n = 20). Patients with potentially correlated sys temic diseases were excluded. Main Outcome Measures: Surface expressio n of platelet P-selectin and circulating level of interleukin (IL) 1 b eta, 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 (1.2 4 +/- 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 con trols. The serum levels of IL-1 beta, 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 signifi cant difference in the serum levels of IL-1 beta (7.2 +/- 4.9 pg/mL), TNF-alpha (12.9 +/- 3.47 pg/mL), and IL-8 (5.9 +/- 4.13 pg/mL) was obs erved in patients with LV compared with controls. An increased express ion of platelet P-selectin was also detected in patients with LV in co mparison with controls and patients with CSVV. The mean +/- SD percent age of positive cells for P-selectin was 43% +/- 5% in the patients wi th LV, 5.1% +/- 2% in the controls (P<.001), and 5.3% +/- 2% in the pa tients with CSVV (P<.001). Conclusions: Taken together, these data dem onstrate that different pathogenetic mechanisms are operative in LV an d 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 vasculiti s.