​Nail Disorders and Abnormalities

Some common nail disorders

Ingrowing toenail

A common problem resulting from various causes – eg, improperly trimmed nails, hyperhidrosis and poorly fitting shoes.

It often presents with pain but may progress to infection and difficulty with walking.

Treatment options include cutting Nails Square, hot water soaks, antibiotics or excision and wedge excision or total excision of nail. A Cochrane review found that surgical treatments were more effective than non-surgical treatments.

Beau’s lines

Transverse ridges are usually transient and due to a temporary disturbance of nail growth – eg, severe illness.

Green nails

These are caused by pseudomonal infection.

Blue nails

They may occur as a side-effect of anti-malarial drugs.

Black nails

These may be a feature of Peutz-Jeghers syndrome, vitamin B12 deficiency and post-irradiation.

Black streaks may indicate a junctional melanocytic naevus or malignant melanoma.

Leukonychia (white nail)

This may be congenital or due to minor trauma, hypoalbuminaemia in chronic liver disease, renal failure, fungal infection or lymphoma.

Yellow nail syndrome

Yellow nail syndrome is characterised by slow-growing, excessively curved and thickened yellow nails, which are associated with peripheral lymphoedema and exudative pleural effusions.

Clubbing

An increase in the soft tissue of the distal part of the fingers or toes; common causes of finger clubbing include:

Cyanotic congenital heart disease, infective endocarditis.

Lung cancer, pulmonary fibrosis, cystic fibrosis, bronchiectasis, empyema, lung abscess.

Koilonychia

Dystrophy of the fingernails in which they are thinned and concave with raised edges (spoon-shaped nails). May be due to iron deficiency or trauma.

Nail-patella syndrome

A congenital nail disorder, autosomal dominant inheritance.

The patellae and some of the nails are rudimentary or absent.

Longitudinal ridging

Causes include alopecia areata, lichen planus, rheumatoid arthritis and peripheral vascular disease.

Onycholysis

The nail becomes detached from its bed at the base and side, creating a space under the nail that accumulates dirt. Air under the nail may cause a grey-white colour but can vary from yellow to brown. In psoriasis can see a yellowish-brown margin between the margin between the normal nail (pink) and the detached parts (white).

If Pseudomonas aeruginosa grows underneath the nail, then green colour.

When nail bed separation begins in the middle of the nail then appearance resembles an ‘oil spot’ or ‘salmon-patch’.

Causes of onycholysis include:

Idiopathic or inherited

Systemic disease – eg, thyrotoxicosis

Skin disease – eg, psoriasis

Local causes – eg, trauma or chemicals

Onychogryphosis

Thickening of the nail plate is mainly seen on big toes of the elderly, associated with injury to the foot, badly fitting shoes or poor blood supply.

Median nail dystrophy

Central grooves in the centre of the nail. Also, the cuticle is pushed back and inflamed. Most commonly results from the compulsive habit of a patient picking at a proximal nail fold thumb with an index fingernail.

Disappears if patient stops the habit.

Splinter haemorrhages

Splinter haemorrhages are linear haemorrhages lying parallel to the long axis of fingernails or toenails.

Causes include:

Trauma

Infective endocarditis

Vasculitis – eg, rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa

Haematological malignancy Severe anaemia

Psoriasis

Virtually all patients with psoriasis have nail involvement at some time and it occurs in 50% of cases at any given time.

Abnormalities include nail pits, transverse furrows, crumbling nail plate, roughened nails.

Nail pitting is associated with alopecia areata as well as with psoriasis. Can sometimes be seen in nail bed ‘oil spot’, distal onycholysis, distal subungual hyperkeratosis, splinter haemorrhages and false nail following spontaneous separation of nail plate.

Lichen planus

Nails are involved in approximately 10% of cases of disseminated lichen planus. However, may be only presentation of disease.

Within the matrix causes thinning, brittleness, crumbling of the nail with accentuated surface longitudinal ridging and colour change to black or white.

Typically the lunula is raised more than the distal part of the nail.

Severe chronic inflammation causes either partial or complete loss of nail plate and formation of pterygium (see picture below) with partial loss of central nail plate seen as distal notch or completely split nail. Involvement of the nail bed causes onycholysis, distal subungual hyperkeratosis, formation of bulla or permanent anonychia.

Treatment: Injection of steroid into proximal nail fold is the conventional treatment. Successful treatment with etanercept has been reported.

Nail tumours

Squamous cell carcinoma (SCC)

This is usually caused by infection with human papillomavirus types 16 and 18. Skin-coloured or hyperpigmented lesions appearing as keratotic or hyperkeratotic or warty papules and plaques found on the proximal and lateral nail folds and hyponychium.

SCC in situ (SCCIS) can extend into the nail bed producing onycholysis.Invasive SCC arising within SCCIS can cause pain if it invades bone.

Occurs much more commonly on fingers, usually the thumb and index finger, usually as a solitary lesion. Can involve multiple fingers in immunocompromised patients.

Treat with CO₂ laser ablation, Mohs’ surgery or amputation of the digit if necessary

Nail matrix naevomelanocytic naevus

Presents as a longitudinal brown strip in the nail bed.

Acrolentiginous melanoma

Mostly seen in the thumb and big toe with brown-black pigmentation of the nail extending to the proximal and lateral nail folds and even beyond the nail (Hutchinson’s sign), usually without other symptoms.

Mean age of patients is 55-60 years.

Cause of 2-3% of melanomas in white patients and 1 in 5 or 6 black patients. Diagnosis is by biopsy. Five years survival is 35-50%.

Fungal nail infections – onychomycosis

Paronychia

Paronychia is inflammation of the tissue around the fingernail, with pus accumulating between the cuticle and the nail matrix. The area may become swollen, red and tender. Acute paronychia is usually due to bacterial infection, particularly Staphylococcus aureus. Chronic paronychia may be associated with eczema or psoriasis. It is often due to candidal infection but other pathogens – eg, Pseudomonas spp. (producing a green or black discolouration) – may be the cause.

Acute paronychia

Erythema, swelling and throbbing pain in the nail fold caused by bacterial infection – eg, S. aureus and Group A streptococci.

Chronic paronychia

Commonly occurs in patients whose hands are constantly in water with repeated minor trauma damaging the cuticle so that irritants can further damage the nail fold.

Proximal and lateral nail folds show erythema and oedema with loss of cuticle and part of proximal nail fold separating from the nail plate.

Commonly becomes infected, especially with Candida albicans. Eventually the nail fold retracts and becomes thickened and rounded.

There are episodes of painful acute inflammation often due to infection between the proximal nail fold and nail plate from which pus may drain.

Over time, lateral edges of the nail plate become irregular and discoloured and eventually the entire nail plate becomes involved showing numerous transverse grooves.

Removing the source of the irritation is the most important aspect of treatment.

Topical steroids appear to be better than oral antifungals.