Yesterday's Medical Challenge answer was clear to some readers and a mystery to others. The answer was:
#4 Yellow Nail Syndrome. Although nails can become discolored from nail polish, the medical Yellow Nail Syndrome is a sign of a serious disorder and not well understood. It is believed to be associated with restrictive lung disease or (rarely) problems with lymphatic drainage channels. (good memory, Grady Doc!)
Thanks for your diagnosis in this challenging case!