Is there a difference between habit tic and median canaliform nail dystrophy of Heller?

Heller’s Median canaliform nail dystrophy (MCD) and habit tic deformity (HTD) are often confused with each other, although there are distinct differences between the two conditions. MCD is characterised by a median break in the nail and obliquely-proximally running furrows without a longitudinal depression. Signs of skin picking are lacking. HTD shows longitudinal shallow and wide depression with innumerable short transverse lines, due to repeated pressure on the nail matrix as a result of repeated pushing of the proximal nail fold’s free margin back.