Onycholysis indicates separation of the nail plate from the distal nail bed.
Common causes are
- chronic exposure to moisture,
- fungal infection (distal onycholysis),
- atopic or contact dermatitis,
- drugs (bleomycin, vincristine, retinoid agents, indomethacin, chlorpromazine [Thorazine]), and
- drug-induced phototoxicity from tetracyclines or chloramphenicol.
Beau lines are transverse grooves in the nail plate that represent a temporary disruption of formation of the nail plate. The lines 1st appear a few weeks after the event that caused the disruption in nail growth. A single transverse ridge appears at the proximal nail fold in most 4–6 wk old infants and works its way distally as the nail grows; this line may reflect metabolic changes after delivery.