Nail alterations are common in systemic diseases, but most of them are not specific. Typical nail signs for systemic disease are rare, but should not be missed. Some nail signs should suggest a systemic disease, especially if present on several digits: Beau's lines, onychomadesis, splinter hemorrhages, clubbing, apparent leukonychia, abnormal nail fold capillaries, melanonychia, red lunula and pterygium inversum unguis.