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Onychomycosis in Child
See also in: Nail and Distal Digit
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Onychomycosis in Child

See also in: Nail and Distal Digit
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Contributors: Vivian Wong MD, PhD, Shari Lipner MD, PhD, Susan Burgin MD, Craig N. Burkhart MD, Dean Morrell MD
Other Resources UpToDate PubMed


Onychomycosis is a fungal infection of the nail (tinea unguium). Onychomycosis accounts for approximately 30% of all nail diseases in children. The prevalence of onychomycosis in children varies from 0.2%-2.6% (mean 0.3%). The low prevalence in children compared with adults is thought to be due to children's fast nail plate growth and their lower incidence of tinea pedis compared with adults. The predisposing factors are a family history of onychomycosis or tinea pedis, atopic dermatitis, psoriasis, Down syndrome, diabetes, obesity, malignancy, hyperhidrosis, trauma, occlusive footwear, contact with a household member with onychomycosis, and immunosuppression due to human immunodeficiency virus (HIV) infection or medications.

Onychomycosis is more common on the toenails as opposed to the fingernails. Onychomycosis is classified by the mode and site of invasion, and there are types of pediatric onychomycosis in the current classification.

Distal lateral subungual onychomycosis (DLSO), the most common form (60%-65% of childhood cases), begins with fungal invasion of the hyponychium and spreads proximally along the nail bed to the nail plate. In Western countries, DLSO is mainly due to Trichophyton rubrum.

Superficial white onychomycosis (SWO) is due to fungal invasion of the dorsal nail plate. In children, SWO is typically caused by T rubrum. It accounts for 8%-28% of cases.

Proximal subungual onychomycosis (PSO) is caused by invasion of the proximal nail fold. In the absence of paronychia, PSO is typically due to T rubrum.

Endonyx onychomycosis (EO) presents as lamellar nail splitting and milky patches of the nail plate. The fungus directly invades the nail plate, but there is no penetration of the nail bed. The most common organisms are Trichophyton soudanense and Trichophyton violaceum.

Total dystrophic onychomycosis (TDO) is the most severe form and is rarely seen in children. It may be primarily seen in the setting of an immunodeficiency such as chronic mucocutaneous candidiasis, or it may be secondary to the culmination of any of the other types of onychomycosis.

In children, T rubrum is the most common causative organism. Other organisms include Trichophyton mentagrophytes, Microsporum canis, and Trichophyton tonsurans.

Less commonly, Candida spp. may cause onychomycosis. More commonly, Candida spp. are cultured along with T rubrum.

Rarely, other nondermatophyte molds are responsible for onychomycosis. Aspergillus and Acremonium species and Scytalidium hyalinum present with white nail discoloration, either in a superficial white or proximal subungual pattern.

Mixed clinical pictures involving more than one type may occur.

Majocchi-like granulomas, deep ulcerated fungal infections, severe tinea capitis and corporis, and fungal nail involvement are characteristic of an inherited deficiency of CARD9 (caspase recruitment domain-containing protein 9), an inflammatory cascade-associated protein. The disorder is autosomal recessive and is most common in North African countries including Algeria, Morocco, and Tunisia. The infections usually begin in childhood and are caused by T rubrum and T violaceum. Lymphadenopathy, high immunoglobulin E (IgE) antibody levels, and eosinophilia are common, and the disorder can be fatal.


B35.1 – Tinea unguium

414941008 – Onychomycosis

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Differential Diagnosis & Pitfalls

  • Nail psoriasis – Multiple large, coarse, and deep pits randomly scattered on the nail plate; onycholysis (detachment of the nail plate from the nail bed) surrounded by an erythematous border; yellowish or salmon pink patches on the nail bed; subungual hyperkeratosis; and splinter hemorrhages. (Nail psoriasis and onychomycosis may coexist.)
  • Trauma
  • Subungual exostoses
  • Verruca
  • Paronychia secondary to finger sucking or nail biting
  • Twenty-nail dystrophy, or trachyonychia – Clinical sign is characterized by rough nail surface with marked longitudinal striations resulting in splitting.
  • Pachyonychia congenita – Marked subungual hyperkeratosis with accumulation of hard keratinous material resulting in uplifting of the nail plate.

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Last Reviewed: 06/20/2019
Last Updated: 06/24/2019
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Onychomycosis in Child
See also in: Nail and Distal Digit
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Onychomycosis : Fingernails, Subungual debris, Toenails, Onycholysis, Nail thickening
Clinical image of Onychomycosis
Thickened fourth fingernail with distal loss of nail and subungual hyperkeratosis.
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