History:

 Median Canaliform Dystrophy of Heller (Median Nail Dystrophy) is a rare but morphologically striking habit tic deformity of thumb nails characterized by midline longitudinal furrow with multiple transverse parallel lines. The proposed etiopathogenesis is repetitive trauma to the nail plate and cuticle, however some cases are familial and some others have been reported with use of oral retinoids.