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.

Leukonychia is a white opacity of the nail plate that may involve the entire plate or may be punctate or striate. The nail plate itself remains smooth and undamaged.

Leukonychia can be traumatic or associated with infections such as leprosy and tuberculosis, dermatoses such as lichen planus and Darier disease, malignancies such as Hodgkin disease, anemia, and arsenic poisoning (Mees lines).

Leukonychia of all nail surfaces is an uncommon hereditary autosomal dominant trait that may be associated with congenital epidermal cysts, renal calculi, and deafness.

Paired parallel white bands that do not change position with growth of the nail and thus reflect a change in the nail bed are associated with hypoalbuminemia and are called Muehrcke lines.

When the proximal portion of the nail is white and the distal 20–50% of the nail is red, pink, or brown, the condition is called half-and-half nails or Lindsay nails; this is seen most commonly in patients with renal disease but may occur as a normal variant.

White nails of cirrhosis, or Terry nails, are characterized by a white ground-glass appearance of Continue reading »