Nail terminology

Author: Dr Amanda Oakley, Clinical Associate Professor, Waikato Clinical School, Hamilton, New Zealand, 1997.

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 ageing, 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 the 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 a 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 haemorrhage or haematoma (blood clot) causes a purple or black discolouration.

Black nail

A black nail may be due to a 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 the 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 thyroid 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 acitretin treatment.