CEACAM1 and dysplastic nevus: Immunohistochemical studies conducted by Gambichler and collaborators comparing CEACAM1 expression in benign and malignant melanocytic tumors and normal peritumoral skin reported a progressive increase of median CEACAM1 expression from 1% in benign nevi and 9.6% in dysplastic nevi to 18% in thin superficial melanomas (defined as melanomas with Breslow tumor thickness <1 mm) and 74% in thick superficial spreading melanomas (defined as melanomas with Breslow tumor thickness >1 mm) (p < 0.0001) [80].