Erosion of the nail plate and tenderness of the fingertip may have several causes, the most common being onycholysis, a spontaneous separation of the nail plate from the underlying skin. It classically occurs at the distal end of the nail and can be quite painful. It is a common condition, primarily occurring in females and in the elderly. Treatment consists of avoiding trauma to the nail, avoiding irritants and keeping the nail dry.
Another common condition is fungal infections of the nail (medical term: onychomycosis), and this should be considered especially if the condition is spreading to other nails, as is the case with this reader. Note that dermatologists often see patients with obvious clinical evidence of fungal even though the lab tests are negative, so a course of oral anti-fungal therapy might still be indicated. There are also a whole host of other conditions that your dermatologist could consider, including bacterial infections, eczema, psoriasis and even warts beneath the nail. These are far too numerous to list here, but your dermatologist should be familiar with the most common ones.
You should also realize that many nail disorders are extremely difficult to treat since the nail plate is not "living" tissue. Many nail disorders are incurable, but pain or tenderness should be relieved with appropriate therapy.
comment by Dr. Julian Schamroth, a veteran Jerusalem dermatologist
