Nail Separation

Onycholysis indicates separation of the nail plate from the distal nail bed.

Common causes are 

• trauma, 
• chronic exposure to moisture, 
• hyperhidrosis, 
• cosmetics, 
• psoriasis, 
• fungal infection (distal onycholysis), 
• atopic or contact dermatitis, 
• porphyria, 
• 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. At other ages, Beau lines are usually indicative of periodic trauma or episodic shutdown of the nail matrix secondary to a systemic disease such as measles, mumps, pneumonia, or zinc deficiency.

Onychomadesis is an exaggeration of Beau lines leading to proximal separation of the nail bed.