Beau’s lines are transverse depressions of all of the nails that appear at the base of the lunula weeks after a stressful event has temporarily interrupted nail formation.The lines progress distally with normal nail growth and eventually disappear at the free edge. They develop in response to many diseases, such as syphilis, uncontrolled diabetes mellitus, myocarditis, peripheral vascular disease, and zinc deficiency, and to illness accompanied by high fevers, such as scarlet fever, measles, mumps, and pneumonia.