CEACAM1 and lichen planus: In oral tissues, CEACAM1 was detected in sulcular epithelium sites affected by periodontitis and junctional epithelium in healthy subjects.13 Some investigators reported that up-regulation of CEACAM1 is associated with development of chronic immune-mediated diseases, such as psoriasis and lichen planus, and also chronic inflammatory diseases such as Crohn’s disease14,31,32.