I have this prominently on my big toe nails, but also a little on my thumb nails. It could be mistaken for fungus but isn't cos the meds didn't work and the test was negative. Doc gave me a cream made of Urea to help with moisture but it did nothing (except it works very well on the hard skin on my feet! ) It looks like ridges, but when you look closer you can see little elongated flat lumps that"grow" up the nail (from the base up to where you cut it) in straight lines. It looks like a line of tiny, long lumps, and there's lots of lines (of tiny, long lumps) going up the nail from the base to the tip.  It's so much that my nail flakes at the top so I have to keep them trimmed really really short. The same is on my thumbs, but it's very slight. It's getting worse and is unsightly. Any clues?