median nail dystrophy
median nail dystrophyA nail disorder characterised by a paramedian canal or split in the nail plate of one or more nails. Small cracks or fissures extend laterally from the central canal or split toward the nail edge, resulting in an appearance likened to that of an inverted Christmas tree. The condition is usually symmetrical and most often affects the thumbs.
Usually idiopathic; some cases have been linked to trauma, the use of PDAs (personal digital assistants) and isotretinoin.