Trachyonychia and Twenty-Nail Dystrophy: A Comprehensive Review and Discussion of Diagnostic Accuracy.

BACKGROUND/AIMS The term trachyonychia, also known as twenty-nail dystrophy, is used to describe thin, brittle nails with excessive longitudinal ridging. The term twenty-nail dystrophy has been incorrectly applied to other conditions that can affect all twenty nails. Therefore, we have conducted a comprehensive review of the clinical features of trachyonychia and have included a discussion regarding the diagnostic accuracy of this condition in the literature. METHODS In November and December 2015, we conducted a thorough literature search using the following search terms: 'trachyonychia', 'twenty nail dystrophy', and 'sandpaper nails'. Articles that reported the epidemiology, disease associations, clinical presentation, histopathology, and treatment options for trachyonychia were included. Particular attention was given to case reports to identify misdiagnosed cases of twenty-nail dystrophy. RESULTS Our preliminary search yielded 184 results with 72 unique articles ultimately selected for review. Excluded articles included 27 articles in languages other than English, 18 commentaries or reviews, and 67 irrelevant articles. Twelve additional articles described nail abnormalities clinically different from trachyonychia. CONCLUSION Many other conditions can cause widespread nail dystrophy. The specific characteristics of trachyonychia need to be considered to make the diagnosis of twenty-nail dystrophy.