Once a student asked me a question. Is there a disease regarding the field of Oral Medicine, which by not knowing one cannot truly become an Oral Physician? I smiled and said "Oral Lichen Planus". Lichen planus is the most common immune mediated chronic inflammatory muco-cutaneous disease that gets its utmost importance in being the oral component life long (as the disease is still idiopathic and hence having no cure) and being a potentially malignant disorder.