Wikipedia
Onychotillomania
Onychotillomania is a compulsive neurosis in which a person picks constantly at the nails or tries to tear them off. It is not the same as onychophagia, where the nails are bitten or chewed or dermatillomania, where skin is bitten or scratched.
It is commonly associated with psychiatric disorders such as depressive neurosis, delusions of infestation and hypochondriasis.
It was named by Professor Jan Alkiewicz, a Polish dermatologist.
The constant destruction of the nail bed leads to onychodystrophy, paronychia and darkening of the nail.
Some cases have been treated successfully with antipsychotics.