Figure 5. Clinical, microscopic, and immunhohistochemical analyses of Case 3. A: Skin biopsyshowed an extensive pattern of pauci-inflammatory vascular thrombosis with endothelial cellinjury. (Hematoxylin and eosin, 400x.) B: Prominent deposits of C5b-9 are seen within themicrovasculature. (Diaminobenzidene, 400x). C: Striking retiform purpura with surroundinginflammation was noted on the buttocks.