Onychoschizia - Nail and Distal Digit
Onychoschizia has been observed in around 9% of pregnant individuals and represents the second most common nail finding in pregnancy along with onychocryptosis (9%) and leukonychia (24.4%).
Brittle nails have also been associated with systemic diseases, including endocrinopathies, tuberculosis, Sjögren syndrome, and malnutrition. Onychoschizia is a common finding in Sézary syndrome and, along with anonychia and distal notching, may differentiate from the nail findings in early mycosis fungoides. (The most common nail findings seen in early mycosis fungoides are longitudinal ridging, nail thickening, nail fragility, and leukonychia.)
The horizontal splits are most commonly seen in the distal portion of the nail and nail edge; proximal onychoschizia has been observed in patients with psoriasis or lichen planus and in those on oral retinoid therapy.
Toenail onychoschizia has been observed in around one-third of newborns younger than 5 days, and fingernail and toenail involvement is seen in 2.4% of children aged 0-2 years. In the fingernails, thumb sucking is thought to be contributory. It is thought that this splitting is secondary to the thin nails in newborns and children that are easily separated with minor trauma. It resolves as the child gets older.
L60.3 – Nail dystrophy
82144009 – Lamellar nail splitting
- Onychorrhexis – Longitudinal grooves, ridges, or splits may occur concurrently with onychoschizia, characteristic of brittle nails, or on its own in diseases that involve the nail matrix such as lichen planus, Darier disease, psoriasis, atopic dermatitis, pityriasis rubra pilaris, and alopecia areata.
- Trachyonychia (rough nails) is characterized by severe accentuation of longitudinal ridging with tiny adherent scales giving the entire nail the appearance of having been sandpapered. A milder variant with miniscule punctate depressions may make the longitudinal ridging appear shiny. Trachyonychia may involve one or all nails, and it may be idiopathic or associated with inflammatory skin conditions including alopecia areata, lichen planus, psoriasis, or atopic dermatitis.
- Fungal infection (onychomycosis) or psoriasis may give the nail plate a friable or brittle appearance.
- Regular linear nail pits may form horizontal ripples or longitudinal ridges.