Abnormal nail surface Beau's lines A nail dystrophy that is preseents as grooved lines that run from side to side on the fingernail or the toenail that may look like indentations or ridges on the nail plate. They are caused by temporary disruption in the growth of proximal nail matrix. Trauma is usually the initiating factor such as infections, severe medical illnesses, major surgery/anesthesia, medication side effects, and autoimmune disease. Ladder nail Ladder nail sign Beau lines