S100A4 and incontinentia pigmenti: Based on the results of the ROC curve analysis of the S100A4 levels in predicting postoperative AE of IP (area under the curve [AUC], 0.871; 95% CI, 0.799–0.943; P < 0.001; Fig. 2), a cutoff value of 17.13 ng/mL was used to divide patients into two groups: 50 patients with high S100A4 levels (≥ 17.13 ng/mL) and 112 with low S100A4 levels (< 17.13 ng/mL).