Thrombosis in small and medium-sized pulmonary arteries in Wegener's granulomatosis: a confocal laser scanning microscopy study.

OBJECTIVE Wegener's granulomatosis (WG) can cause endothelial cell damage and thromboembolic events. Nevertheless, there have been few studies on the pulmonary microcirculation--small and medium-sized pulmonary arteries (SMSPA)--in patients with WG. The objective of this study was to quantify fibrin thrombi in the SMSPA of patients with WG. METHODS We analyzed 24 SMSPA samples collected from six patients with WG and 16 SMSPA samples collected from four patients without WG. In all samples, we used the endothelial cell marker CD34 and confocal laser scanning microscopy in order to detect intravascular fibrin thrombi. We calculated the total vessel area, the free lumen area, and the thrombotic area. RESULTS The mean total vessel area was similar in the WG and control groups (32,604 µm² vs. 32,970 µm², p = 0.8793). Thrombi were present in 22 (91.67%) of the 24 WG group samples and in none of the control group samples (p < 0.0001; OR = 297; 95% CI: 13.34-6,612). The mean thrombotic area was greater in the WG group samples than in the control group samples (10,068 µm² vs. 0.000 µm²; p < 0.0001). In contrast, the mean free lumen area was smaller in the WG group samples than in the control group samples (6,116 µm² vs. 24,707 µm²; p < 0.0001). CONCLUSIONS Confocal laser scanning microscopy revealed a significant association between pulmonary microvascular thrombosis and WG. This suggests a possible role of microvascular thrombosis in the pathophysiology of pulmonary WG, evoking the potential benefits of anticoagulation therapy in pulmonary WG. However, further studies are needed in order to confirm our findings, and randomized clinical trials should be conducted in order to test the role of anticoagulation therapy in the treatment of patients with pulmonary WG.