Nail Disorders and Abnormalities

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Ingrowing (Ingrown) Toenails written for patients

Nail abnormalities are common. Appearances may be difficult to diagnose with certainty, and care must be taken to ensure correct diagnosis and therefore treatment.

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.[2]

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.

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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.


  • 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.


  • 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.
  • 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
  • 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.
  • 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 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
  • 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.
  • 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.
  • Lichen planus can affect any number of nails.
  • Treatment:
    • Injection of steroid into proximal nail fold is the conventional treatment.
    • Successful treatment with etanercept has been reported.[9] 

Squamous cell carcinoma (SCC)[10]

  • 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.
  • Successful use of electronic brachytherapy has been reported.[11]

Nail matrix naevomelanocytic naevus[5]

  • Presents as a longitudinal brown strip in the nail bed.

Acrolentiginous melanoma[12]

  • 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%.

See separate article Fungal Nail Infections.

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. There is a new surgical treatment called the Swiss roll technique (the nail fold is elevated and reflected proximally over a non-adherent dressing).[13]

Further reading & references

  1. Nail Disorders; Nail Disorders
  2. Eekhof JA, Van Wijk B, Knuistingh Neven A, et al; Interventions for ingrowing toenails. Cochrane Database Syst Rev. 2012 Apr 18;4:CD001541. doi: 10.1002/14651858.CD001541.pub3.
  3. Jadhav VM, Mahajan PM, Mhaske CB; Nail pitting and onycholysis. Indian J Dermatol Venereol Leprol. 2009 Nov-Dec;75(6):631-3. doi: 10.4103/0378-6323.57740.
  4. McDermott R et al; International Journal of Case Reports and Images, Vol. 3 No. 1, January 2012
  5. Baran R et al; A Text Atlas of Nail Disorders, 2003
  6. Fawcett RS, Linford S, Stulberg DL; Nail abnormalities: clues to systemic disease. Am Fam Physician. 2004 Mar 15;69(6):1417-24.
  7. Ayala F; Clinical presentation of psoriasis. Reumatismo. 2007;59 Suppl 1:40-5.
  8. Nakamura R, Broce AA, Palencia DP, et al; Dermatoscopy of nail lichen planus. Int J Dermatol. 2013 Jun;52(6):684-7. doi: 10.1111/j.1365-4632.2011.05283.x. Epub 2013 Feb 22.
  9. Irla N, Schneiter T, Haneke E, et al; Nail Lichen Planus: Successful Treatment with Etanercept. Case Rep Dermatol. 2010 Oct 21;2(3):173-176.
  10. Peterson SR, Layton EG, Joseph AK; Squamous cell carcinoma of the nail unit with evidence of bony involvement: a multidisciplinary approach to resection and reconstruction. Dermatol Surg. 2004 Feb;30(2 Pt 1):218-21.
  11. Arterbery VE, Watson AC; An electronic brachytherapy technique for treating squamous cell carcinoma in situ of the digit: a case report. BMC Res Notes. 2013 Apr 15;6(1):147.
  12. Wich LG, Ma MW, Price LS, et al; Impact of socioeconomic status and sociodemographic factors on melanoma presentation among ethnic minorities. J Community Health. 2011 Jun;36(3):461-8. doi: 10.1007/s10900-010-9328-4.
  13. Relhan V, Goel K, Bansal S, et al; Management of Chronic Paronychia. Indian J Dermatol. 2014 Jan;59(1):15-20.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Colin Tidy
Current Version:
Peer Reviewer:
Dr Hannah Gronow
Document ID:
1096 (v24)
Last Checked:
Next Review:

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