Patient Presentation
A 15-month-old male came to clinic for his health supervision examination. He was well but the mother was concerned about white spots on his fingernails. His previous doctor had told the mother that they were not a problem but the infant should take a multivitamin which she says he took every day. She was concerned because they were not going away. The past medical history was non-contributory. The pertinent physical exam showed a healthy toddler with normal vital signs and growth parameters in the 5-15%. He had normal appearing toenails. On 3 fingers he had small whitish grouped spots. The groupings were at the same location on each finger and did not change with pressure. There was no ridging of the nails and the nail folds appeared normal.

The diagnosis of leukonychia was made. The parent was educated that the spots were common problems encountered by children often because of trauma. That they were grouped at the same location on each hand indicated that they all probably occurred at the same time. The parent was told that the multivitamin could be continued but it would not make any difference in the nails and that the spots would grow out over time.

Discussion
The nail matrix covers the area of the nail plate, and extends proximally in a crescent moon shape with the edges of the crescent extending proximally and inferiorly toward the underlying bone. The nail matrix is a multilayered epithelium that physiologically produces keratinization and gives rise to the nail plate. The distal matrix forms the lower 2/3s of the nail plate and the proximal matrix forms the upper 1/3 of the nail plate. the thickness of the nail plate is proportion to the matrix’s thickness. The nail plate’s free edge contour follows the shape of the nail’s lunula. Melanocytes occur in the nail matrix but are 1/6 as numerous as those in the skin epidermis. In the distal matrix about 50% are activable and 50% are dormant. In the proximal matrix almost 100% are dormant. If activated, the melanocytes produce pigment, which is transferred to the keratin and a colored area of the nail plate occurs.

Regrowth of fingernails takes about 6 months and toenails can be 12-18 months. It usually takes 4-8 weeks for any incident to even begin to show up on the nails.

Learning Point
Leukonychia means white nail. It occurs when the normally translucent color is gone and the nail plate looks totally or partially white.

• True leukonychia has abnormal keratinization of the nail plate so that the nail plate appears white because of changes in the light diffraction. The coloring does not change with pressure, and the opacity changes with nail growth.
• Apparent leukonychia has an abnormal nail bed vasculature so that the nail plate appears white. The coloring changes with pressure and the opacity does not change with nail growth.
• Pseudoleukonychia when there the cause is not the mail matrix nor vasculature but is a surface problem such as superficial onychomycosis or keratin granulations.

If a patient has extensive changes to the nail plate then more evaluation or referral is needed including complete blood count, metabolic panel and heavy metal screening and possible dermatology referral.
Treatment is eliminating the underlying cause particularly gentle (instead of rough) manipulation of the digits and less frequent use of irritating products such as artifical nails or nail polish remover.

Different forms of leukonychia include:

• Punctate leukonychia
  • True leukonychia
  • Usually least severe form of leukonychia
  • Solitary or grouped spots usually on the fingernails
  • Causes
    • Trauma***
    • Idiopathic childhood
    • Psoriasis
• Transverse leukonychia
  • True leukonychia
  • Parallel to the nail bed or lunula and usually spans the across the entire nail bed
  • Transverse leukonychia is often referred to as Mee’s lines after Mee’s who reported it in arsenic poisoning
  • It is often an incidental finding in children because of unnoticed trauma
  • They can be found on young infant’s fingernails about 8-12 weeks after birth also.
  • Causes
    • Trauma***
    • Heavy metal poisoning – arsenic, thallium
    • Drug therapy including chemotherapy, radiation
    • Systemic disease
      • Cancer
      • Heart failure
      • Infection – measles, tuberculosis, HIV, parasites
      • Renal failure
      • Systemic lupus erythematosus
      • Ulcerative colitis
    • Hypoalbuminemia
      • Muehrcke lines are paired transverse lines that are associated with periods when the body is not able to synthesize proteins as well, such as malnutrition, liver disease, etc.
      • Chemotherapy
      • HIV
      • Liver disease
      • Malnutrition
      • Organ transplant
• Longitudinal leukonychia
  • True, apparent or pseudo- leukonychia depending on location of origin
  • Occurs perpendicular to the nail bed or lunula, running along the axis of the digit itself. Causes “stripes”
  • Causes
    • Darier disease – “candy-cane” appearance with alternating red and white streaks
    • Hailey-Hailey disease – multiple white stripes
    • Half and Half nails
      • White and red/brown band alternating
      • Kidney transplant but not hemodialysis
      • Behcet’s disease
      • Crohn’s disease
      • Chemotherapy
      • Liver failure
      • Kawasaki disease
      • Pellegra
      • Zinc deficiency
    • Onchopapilloma
    • Onchomycosis
• Partial or total leukonychia
  • True leukonychia that is uncommon
  • Causes
    • Congenital
    • Terry nails
      • Ground glass appearance that affects about 75% of the nail. lunula is not seen.
      • Liver failure
      • Diabetes
      • Heart failure
      • Peripheral vascular disease
      • Reactive arthritis
      • Tuberculosis

** – Trauma is the most common cause including manipulation of the digits, artifical nails, irritants such as nail polish remover, nail glue, etc.

Questions for Further Discussion
1. What are Beau’s lines and what are their cause?
2. What causes brown lines and what are their cause?
3. What are signs of potential malignant melanoma of the nails?
4. What causes nail pitting?

Related Cases

Disease: Leukonychia | Nail Diseases

Symptom/Presentation: Pigmentary Lesions

Specialty: Dermatology

Age: Toddler

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Nail Diseases.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Howard SR, Siegfried EC. A case of leukonychia. J Pediatr. 2013 Sep;163(3):914-5.

Richert B, Caucanas M, Andre J. Diagnosis using nail matrix. Dermatol Clin. 2015 Apr;33(2):243-55.

Lipner SR, Scher RK. Evaluation of nail lines: Color and shape hold clues. Cleve Clin J Med. 2016 May;83(5):385-91.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa