dermatologic disorders
Nail Deformities and Dystrophies
Median nail dystrophy (median canaliform dystrophy)
Median nail dystrophy is characterized by small cracks in the nail that extend laterally and look like the branches of an evergreen tree (eg, fir tree, such as a Christmas tree). The cracks and ridges are similar to those seen in habit-tic nail deformity (which is dystrophy of the central nail caused by repetitive trauma to the nail matrix resulting from rubbing or picking with another finger). The cause of median nail dystrophy is unknown in some cases, but trauma is thought to play a role. Frequent use of personal digital devices that subject the nails to repetitive striking has been implicated in several cases.Tacrolimus0.1% at bedtime without occlusion has been successful when patients stop all activities that might lead to repetitive low-level trauma. 