Median CEACAM1 expression was 1% in benign nevi, 9.6% in dysplastic nevi, 18% in thin superficial spreading melanomas (Breslow tumor thickness < 1 mm), and 74% in thick superficial spreading melanomas (Breslow tumor thickness > 1 mm) (p < 0.0001). This evidence concerns the gene CEACAM1 and dysplastic nevus.