Nail terminology
This page outlines the terms used by dermatologists to describe diseases of the fingernails and toenails.
Abnormalities of the nail plate surface
Nail plate abnormalities are often due to inflammatory conditions affecting the matrix or nail bed. Specific diagnoses may be made from characteristic appearances.
Pitting
Pitting may be a sign of eczema, psoriasis and alopecia areata.
Transverse ridging
Transverse ridging may be a sign of eczema, paronychia, psoriasis and parakeratosis pustulosa.
Beau line
Beau line is a transverse depression affecting all nails, due to acute systemic illness stopping nail growth.
Onychorrhexis
Onychorrhexis is longitudinal ridging. Consider aging, lichen planus, psoriasis, fungal nail infection and Darier or a habit of picking.
Longitudinal groove
A central longitudinal groove or median canaliform dystrophy is due to myxoid cyst or wart.
Median canaliform nail dystrophy
This form of median nail dystrophy presents as a feathered, central, longitudinal ridge. Sometimes it is due to repetitively pushing back the cuticle (habit-tic deformity). Macrolunulae (large half-moons) may expose the nail to trauma, as they are frequently present.
Onychogryphosis
Onychogryphosis is a thick hard curved nail plate in the shape of a ram's horn.
due to ageing, psoriasis or trauma.
Onychauxis
Onychauxis is a thick nail due to psoriasis, trauma or fungal nail infection.
Angel-wing deformity
Angel-wing deformity describes nail plate thinning due to lichen planus.
Nail plate crumbling
Nail plate crumbling is typical of psoriasis and fungal nail infection.
Onychoschizia
Onychoschizia is distal lamellar or splitting/brittle nails due to water/detergent damage.
Longitudinal splitting
Longitudinal splitting is an extension of ridging seen in psoriasis, fungal nail infection or lichen planus. Distal splitting in association with a pigmented or red linear band can be a sign of onychopapilloma.
Distal notching
Distal notching of the nail occurs from trauma, Darier disease and lichen planus.
Trachyonychia
Trachyonychia is characteristic of lichen planus.
Erosion
Erosion is due to trauma or malignant tumour eg SCC or melanoma.
Acrylic nails
These images show acrylic nails used as decorative cosmetics.
Nail discolouration
Distinguish a discoloured nail bed from a discoloured nail plate.
Yellow nail syndrome
Yellow nail syndrome refers to yellow or green nails due to lymphatic obstruction in cardiopulmonary disease.
Green nails
Green nails are associated with pseudomonas or candida infection.
Yellow nails due to fungal nail infection
Lateral yellow streak
See onychomycosis.
Yellow nails due to psoriasis
Oil drop or salmon patch
See psoriasis.
Brown nails
If nails are brown coloured, consider staining (nicotine, potassium permanganate, nail varnish) and chemotherapy. Illustrated are staining from podophyllin and streaks due to oral hydroxyurea.
Vitiligo
Leukonychia
White nails. Consider hypoalbuminaemia or chronic renal failure. May be familial. Transverse leukonychia, in which there are multiple parallel white lines, is thought to be due to manicuring. It may also arise in association with Beau lines.
White streaks
These images show white streaks due to trauma, eg manicuring.
Onycholysis
These images show lifting of the distal nail plate, which appears white or yellow. Consider idiopathic causes, trauma, psoriasis, thyrotoxicosis, irritant and allergic contact dermatitis, fungal nail infection (candida), drug photosensitivity (especially tetracycline and psoralens)
White spotting
Superficial white onychomycosis
Half-and-half nails
Half-and-half nails are seen in renal failure. White proximal nail, with brown distal nail.
Terry nail
Terry nail is seen in liver cirrhosis. White proximal nail, reddened distal nail.
Mee lines
Mee lines are partial leukonychia due to arsenic intoxication or systemic disease.
Muehrcke lines
Muehrcke lines are a double band of leukonychia in renal disease.
Red lunula
Red longitudinal streaks
A red longitudinal streak or erythronychia is often due to onychopapilloma.
Red and white streaks
See Darier disease.
Red tender area
If a red spot is tender, consider glomus tumour.
Blue nail
If nails are discoloured blue, consider drugs if all nails are affected, in this case due to minocycline.
Red/purple streak
A red or purple streak is known as a splinter haemorrhage.
Purple/black nail
Subungual haemorrohage or haematoma (blood clot) causes a purple or black discolouration.
Black nail
A black nail may be due to pseudomonas infection
Melanonychia
Melanonychia is a brown/black band due to benign melanocytic naevus.
Multiple brown linear streaks
Longitudinal melanonychia may be of racial origin, Laugier-Hunziker syndrome. Rarely due to drug (azidothymidine, tetracycline), endocrine disorders or Peutz-Jeghers syndrome.
Expanding variable colour/shaped streak
Consider melanoma
Abnormalities of the cuticle and nail fold
The cuticle is an area of keratin joining the skin of the posterior nail fold to the nail plate. Loss of cuticle results in paronychia.
Ragged cuticles
Ragged cuticles are characteristic of connective tissue disease, and also occur in parakeratosis pustulosa.
Hang nail
Hang nail is due to trauma (biting).
Nail fold telangiectases
Nail fold telangiectases are characteristic of connective tissue disease, eg lupus erythematosus.
Vasculitis
Subungual hyperkeratosis
Subungual hyperkeratosis is scaling under hyponychium. Typical of psoriasis and onychomycosis, but also arises in crusted scabies.
Pterygium
A pterygium is a wing of extra tissue. In a nail, it is due to scarring in the matrix. Characteristic of lichen planus, but may also occur in Stevens-Johnson syndrome and after trauma.
Acute paronychia
Staphylococcus aureus is the main cause of acute paronychia.
Acute paronychia
Herpes simplex is another common cause of acute paronychia.
Chronic paronychia
Chronic paronychia is associated with dermatitis, and infection with Candida albicans and pseudomonas.
Acrodermatitis continua of Hallopeau
Acrodermatitis continua of Hallopeau is a form of severe psoriasis
Retronychia
Retronychia refers to embedding of the nail into the nail fold and subsequent inflammation.
Abnormalities of nail shape
Enlarged nail
Long nail
Brachyonychia
Short nail
Over-curvature
Clubbing
Clubbing is due to hypertrophic osteoarthropathy or thryoid disease (acropachy); see hypertrophic osteoarthropathy.
Koilonychia
Koilonychia is a thin, spoon-shaped nail, and can be seen in normal children and adults. It is also associated with iron deficiency anaemia, diabetes, protein deficiency, connective tissue disease, nail exposure to solvents and and acitretin treatment.
Pachyonychia
Pincer nail
Pincer nail is sometimes familial or associated with psoriasis.
Onychocryptosis
Onychocryptosis is an in-growing nail with granuloma formation. Often aggravated by oral retinoids, isotretinoin and acitretin.
Loss of nails
Without scarring
Usually traumatic eg nail biting; in children parakeratosis pustulosa
Scarring
Onychomadesis
Nail-patella-syndrome
Lesions around nails
Common skin lesions around nails include:
Viral warts
Melanocytic naevus
Subungual melanoma
Squamous cell carcinoma or keratoacanthoma
Corn
Subungual fibroma
Inclusion cyst
Onychomatricoma
Subungual exostosis
Giant cell tumour of tendon sheath
Myxoid cyst
Pyogenic granuloma
